Note: Descriptions are shown in the official language in which they were submitted.
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MULTI-FUNCTION END OF TRAIN DEVICE
FOR ELECTRICALLY CONTROLLED
PNEUMATIC FREIGHT BRAKE SYSTEMS
CROSS REFERENCE TO RELATED APPLICATION
This application relates to United States Patent S, 873, 638, Angel P. Bezos,
February 23, 1999.
DESCRIPTION
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention generally relates to infra-train communications for
implementing electrically controlled pneumatic (ECP) railroad freight train
brakes
and, more particularly, to a mufti-function end of train device (EOT) that
operates
in a standard mode in which the EOT functions as a normal EOT, and an ECP
mode providing ECP functionality in an ECP type of EOT device, or in an
emulation mode in which it EOT has 74V tramline power but otherwise functions
as a normal EOT.
Background Description
End of train (EOT) signaling and monitoring equipment is now widely
used, in place of cabooses, to meet operating and safety requirements
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of railroads. The information monitored by the EOT typically includes the
air pressure of the brake line, battery condition and train movement. A
warning light is incorporated into the EOT housing, and the operation of this
warning light is also monitored. This information is transmitted to the crew
in the locomotive by a battery powered telemetry transmitter.
The original EOT telemetry systems were one-way systems that is,
data was periodically transmitted from the EOT to a Locomotive Control
Unit (LCU), sometimes referred to as the Head of Train (HOT) unit,
mounted in the locomotive where the information was displayed. Later
systems are two-way systems in which transmissions are also made by the
LCU to the EOT. In one specific application, the EOT controls an air valve
in the train's brake pipe which can be controlled by a transmission from the
LCU. In a one-way system, service and emergency brake application starts
at the locomotive and progresses along the brake pipe to the end of the train.
I S This process can take signif cant time in a long train, and if there is a
restriction in the brake pipe, the brakes beyond the restriction may not be
actuated. With a two-way system, emergency braking can be initiated at the
end of the train independently of the initiation of emergency braking at the
head of the train, and the process or brake application can be considerably
shortened. As will be appreciated by those skilled in the art, in order for an
LCU to communicate emergency commands to an associated EOT, it is
desirable for the EOT to be "armed"; that is, authorized by railroad
personnel. This is desirable to prevent one LCU from erroneously or
maliciously actuating the emergency brakes in another train. To this end, the
LCU includes a nonvolatile memory in which a unique code identifying an
EOT unit can be stored. The LCU also has a row of thumb wheel switches
which allows manual entry of codes. Additional background on EOT
systems may be had by reference to U.S. Patents No. 5,374,015 and
5,377,938, both to Bezos et al. and assigned to the assignee of this
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application.
The Federal Communication Commission (FCC) allocates blocks of
radio frequencies for railroad communications. The Association of
American Railroads (AAR) then further allocates the frequencies on a
channel basis, which are then used by radio-based infra-train
communications systems. The AAR develops standards for the railroad
industry for, among other things, infra-train communications. Most recently,
the AAR is considering an infra-train communication system in which all
the cars in a consist are hard wired together. In such a system, power to and
communications with the EOT is provided over a cable extending the length
of the train. To this end, the AAR has promulgated draft specifications for
Electrically Controlled Pneumatic (ECP) Freight Brake Systems, revision
#9, November 27, 1996, that requires a special EOT device, hereinafter
referred to as an ECP EOT, as specified on page 2, paragraph 2.1.6. As
specified in that paragraph, this special ECP EOT will contain a "neuron"
chip (a commercially available integrated circuit (IC) chip), a brake pipe
pressure transducer and a battery which will be charged off the train line
voltage. Presumably, this ECP EOT will also need a standard marker
warning light, although the specifications fail to mention this.
Since freight trains can be a mile or more in length, the AAR has
determined that the voltage on the cable must be 230 VDC in order to
provide adequate power to the ECP EOT. To insure safety of personnel and
continuity of the cable, it is necessary to transmit status signals from the
ECP EOT to a Head End Unit (ICU) (as distinguished from an LCU in
non-ECP EOT systems). First, before the 230 VDC power can--be turned on,
it is necessary to insure the safety of personnel to make sure that the cable
has been properly terminated in the ECP EOT and does not pose a shock
hazard. When the cable has been properly terminated, the ECP EOT, under
battery power, listens for a beacon from the HEU and, upon detecting a
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beacon, communicates this to the HEU via the 230 VDC power lines,
confirming continuity of the 230 VDC powez lines and allowing the
engineer to turn the 230 VDC power on or allowing the HEU to
automatically turn the 230 VDC power on. In addition, since the 230 VDC
5 line could be broken either intentionally or accidently, the ECP EOT must
periodically transmit a status message to insure the continued continuity
(i.e., no breaks) of the 230 VDC cable connection, thus further insuring
personnel safety.
The AAR specifications suggest that the ECP EOT should be a
different unit from the currently manufactured standard two-way EOT,
owing in part to the specification for the "neuron" microprocessor and
power line modem transceiver and the fact that the cable interface eliminates
the need for a high capacity rechargeable battery to power the EOT.
However, railroads which use this equipment want to standardize equipment
15 to minimize the logistics of their inventory and maintenance. Manufacturers
of the equipment also want to standardize their products in order to improve
quality and realize savings.
SLfMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a multi-
20 function EOT, or universal EOT (UEOT), that may function conventionally
for those trains not equipped with the 230 VDC ECP power line but which
can automatically change its mode of operation to the ECP EOT function as
defined by the AAR when mounted on trains so equipped.
It is another object of the invention to provide a UEOT with the
25 necessary intelligence to be able to conform to the required multi-
fiinctionality automatically when necessary without operator intervention.
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According to the invention disclosed in U.S. Patent 5, 873, 638, there is
provided an
electronics package or adapter that conforms to the dimensions of the battery
pack of the
standard EOT. This adapter plugs into the battery compartment of the standard
EOT, making
connections with a connector in the battery compartment. When this package is
plugged into
5 the battery compartment, the function of the EOT is changed to conform with
the ECP EOT
function defined by the AAR. This adapter includes a standard ECP connector
connected via
cable to the adapter and extending outside the adapter when mounted in the
battery
compartment. A DC to DC converter reduces a high voltage from the cable to a
low voltage
and supplies the low voltage to a battery charger which maintains a charge on
a small,
rechargeable battery. A " neuron" transceiver connected to the cable and
powered by the
power supply detects when messages are received. Microprocessor electronics
connected to
the " neuron" transceiver and powered by the power supply rersponds to the
detection from the
competition the detection to the HEU via the "neuron" transceiver. The
firmware of the EOT
microprocessor is modified to support the ECP function.
The functionality of the ECP EOT adapter is extended according to another
aspect of
the invention. This extended functionality is implemented in an integrated
Universal EOT, or
UEOT adaptor which, like the ECP EOT adapter, is designed to be mounted in the
battery
compartment of a standard EOT. When the UEOT is mounted, the EOT processor is
powered
on. The EOT processor sends a signal to turn on a separate microcontro(ler
which, in turn,
2 0 powers on the " neuron" microprocessor for a first predetermined period of
time. The
"neuron" microprocessor " listens" for the HEU during this time and if the HEU
beacon is
received, the EOT starts transmitting once per second for a second
predetermined period of
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time. If the HEU receives the EOT transmissions for a third predetermined
period of time, it applies train line power. After this initial power
sequence,
the UEOT operates in one of a plurality of modes, including the standard
mode, the ECP mode and a 74V emulation mode.
In the standard mode, the UEOT functions as a normal EOT with
additional activation of the ECP microcontroller and periodic activation of
the "neuron" microprocessor and periodic train line transmissions to the
HEU. This is the default mode; that is, the UEOT processor enters the
standard mode upon power up and remains in the standard mode until it
receives either an HEU beacon or voltage on the train line, at which point
the unit switches to the ECP mode The UEOT will return to the standard
mode only if there is no train line voltage and no HEU beacons are received
for a predetermined period of time.
In the ECP mode, the UEOT provides the ECP end-of train status
I S transmissions at a predetermined rate on the train line. These status
transmissions contain the prescribed train line voltage, marker status, end-
of train brake. pipe pressure, and battery capacity information for the UEOT
processor.
If HEU beacons are not received but train line voltage in the range of
74V is detected, the UEOT enters the 74V emulation mode in which the
UEOT monitors for failure messages from the cars and relays these
messages to the HEU via radio communications. While in the emulation
mode, the UEOT continues to monitor train line power, and if train line
power in the range of 74V is not detected for a predetermined period of
time, the UEOT reverts to standard mode and again listens for HEU
beacons.
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BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects and advantages will be
better understood from the following detailed description of a preferred
embodiment of the invention with reference to the drawings, in which:
Figure 1 is an elevation view of a standard two-way EOT showing
the location of the battery compartment;
Figures 2A and 2B are, respectively, rear and front views of the
adapter which plugs directly into the battery compartment of the standard
two-way EOT to convert the standard two-way EOT to the ECP EOT
specifications of the AAR;
Figure 3 is a block diagram of the circuitry of the ECP EOT adapter
shown in Figure 2;
Figure 4 is a flow chart showing the modification of the firmware for
the EOT microprocessor;
Figure 5 is an elevation view of the LTEOT according to one aspect
of the invention;
Figure 6 is a block diagram of the circuitry of the LTEOT according
to the invention;
Figure 7 is a flow chart showing the operation of the LTEOT shown
in Figure 6; and
Figure 8 is a flow chart, similar to the flow chart of Figure 7,
showing the operation of the UEOT adapter.
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DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE INVENTION
Referring now to the drawings, and more particularly to Figure 1,
there is shown an elevation view of the standard two-way EOT 10 currently
S manufactured and in widespread use in the raikoad industry. The EOT
illustrated is manufactured by WABCO Railway Electronics (formerly Pulse
Electronics, Inc.), but is representative of two-way EOTs of other
manufacturers as well. The EOT 10 is designed to the mounted on the
trailing coupler of the last car in the train and is equipped with pressure
10 monitoring and telemetry circuitry. Mounting is by means of a coupler hook
mount 1 I which engages a coupler and is clamped in place by a coupler
mount tightening handle 12. A hose 13 is connected between the train's
brake pipe and the EOT unit so that the air pressure of the brake pipe at the
end of the train can be monitored:
1S As shown and described in more detail in U.S. Patents No.
5,374,01 S and 5,377,938, the EOT includes a microprocessor control circuit,
and a nonvolatile memory in which the control program for the
microprocessor controller and a unique identifier code of the particular EOT
are stored. The EOT communicates with a radio transceiver of the lead
20 locomotive by way of its own radio transceiver, the antenna 14 for which is
installed at the top of the EOT. This transceiver and antenna is operational
only when the EOT is used as a standard two-way EOT or in the emulation
mode. The EOT is also provided with a marker warning light 1 S which
flashes periodically and which is monitored by the EOT microprocessor. A
2S carrying handle 16 is provided to allow railroad personnel to carry and
mount the EOT 10.
A battery compartment 17 houses a battery pack (not shown) which
plugs into the battery compartment. The battery pack includes a heavy duty
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rechargeable battery, such as a lead acid battery or a nickel cadmium battery,
and when
plugged in, is retained by clamps or fasteners. As shown in Figure 1, there is
an electrical
connector I 8 in the back of the battery compartment. This connector 18
includes power
contacts to which the battery pack is connected when the battery pack is
plugged into the
battery compartment. The connector 18 also includes additional pins for
interconnecting
signal lines between the adapter and the EOT electronics.
The AAR ECP EOT specification states that the EOT must be connected to the
network and must be transmitting status messages to the HEU before the
trainline power can
be energized. Thus, by implication, the ECP EOT must have its own source of
power (e.g., a
battery) in order to transmit status messages before the 230 VDC power is
turned on.
The adapter disclosed in U.S. Patent No. 5,873,638 is shown in figures 2A and
2B.
Figure 2A shows their rear of the adapter 20 and the mating connector 21 which
plugs into
connector 18 in the back of the battery compartment 17. A flange 23
surrounding the front
base of the battery pack is used to secure the battery pack in the battery
compartment 16.
Figure 2B shows the front of adapter 20. A cable 24 emanates from the face
plate 25 in his
terminated in a 230 VDC connector 26 which is designed to mate with a
corresponding
connector on the cable installed on the railroad car.
Figure 3 is a block diagram of the adapter electronics. Externally, the ECP
230 VDC
connector 26 is connected by the cable 24 to the circuitry of the adapter. The
cable 24
provides a 230 VDC connection to a DC to DC converter 31. The cable 24 is also
connected
via communication isolation 27 to a transceiver 32 which communicates with a
"neuron"
microprocessor 33, as specified by the AAR. The transceiver 32 and "neuron"
microprocessor conform to the specifications of the Echelon Corporation and is
comprised
of two commercially available components. The first is the "neuron" chip
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which is a sophisticated very large scale integrated (VLSI) device that
incorporates communications, control, scheduling and input/output (I/O)
support. The neuron chip enables devices to communicate with one another
using the Echelon LonTalkTM protocol which supports distributed, peer-to-
S peer communication. Neuron chips, model numbers 3120 and 3150, are
manufactured and distributed world wide by Motorola and Toshiba. The
second component is the PLT-10 power line transceiver module, model
50080, which supports the Echelon LonWorksTM power line communication
technology.
10 The DC to DC converter 31 provides a reduced voltage output to
maintains a trickle charge on rechargeable 12 V battery 34. Charging of the
battery 34 by the DC to DC converter 31 is controlled by the
microcontroller 35. Since batteries are inherently not a high reliability
component, it is desirable to maintain dual batteries. This redundancy both
15 increases reliability and capacity. A power converter 37 powered by the
battery {or batteries) 34 produces the required voltages to power the
transceiver 32 and the "neuron" microprocessor 33. The DC to DC converter
31 also supplies train line voltage to a microcontroller 35. The Schotky
diode 36 isolates the battery 34 so that a battery short circuit failure
cannot
affect the operation of the ECP EOT when the ECP EOT is in the ECP
mode, powered by the train line via the DC/DC converter 31.
The battery 34 also provides 12 V power to the EOT microprocessor
via connector pin 40. When the adapter is removed from the battery
compartment, the battery 34 can be charged by a separate battery charger so
25 that the adapter will be fully ready for the mad when plugged into the EOT.
Upon completion of the charging of the battery 34, the battery charger resets
the battery capacity meter 39.
As with a standard EOT, the batteries of the ECP EOT adaptor must
be fully charged before the adaptor is installed in an EOT that is to be
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installed at the end of an ECP train. The reason is that the ECP functionally
needs
battery back-up and since one does not know how long the train line power will
be
"off" prior to departure, the only safe way to operate is to start with fully
charged
batteries. There are two ways to charge the batteries of the adaptors.
The primary method of charging adaptor batteries is to use a standard charger
which connects to pin 40 of the adapter. This approach is preferred because
operators
are familiar with the equipment which gives the operator an indication when
the
batteries are fully charged, The secondary method of charging the batteries is
via
the train line. A drawback of this approach is that it takes a longer time to
charge
the batteries.
The connection between the "neuron" microprocessor 33 and the microcontroller
35 is a parallel input/output (I/O) connections. The microcontroller 35
communicates
with a transceiver 38, which provides the communication link to the EOT
processor and
related circuitry, via a serial connection. This serial connection complies
with an
industry standard, such as the RS232 standard. A battery capacity meter 39
monitors
the charge on battery 34 and is controlled by the microcontroller 35 to
provide data
to the EOT processor and related circuitry. The functions of the battery
capacity
meter 39 may be incorporated into the microcontroller 35 by suitable firmware.
The
connections between the transceiver 38 and battery capacity meter 39 and the
EOT are
made by the roaring of connectors 18 and 21 (Figures 1 and 2).
The modified firmware of the EOT processor causes the EOT to conform to the
multiple functionality. Specifically, when the adapter is plugged into the
battery
compartment, the connection provides the channel for the adapter to notify the
EOT
processor of the presence of the adapter. This notification causes the EOT
firmware
to toggle the operation of the EOT from a standard two-way EOT function to the
ECP EOT
function. That
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is, the EOT stops transmitting via its radio transceiver and provides the ,
brake pipe pressure data via the communication isolation 27 connection
while maintaining the marker light functionality. Of course, when the EOT
does not receive the proper commands via the connection, it functions as a
standard two-way EOT. The modified EOT firmware is illustrated in Figure
4 and described below.
The transceiver 32 detects that the train's 230 VDC cable has been
connected to the EOT in a proper and safe termination of the 230 VDC
cable. This is communicated to the microcontroller 35 which communicates
with the EOT processor via the transceiver 38. In response to a detected
connection to the 230 VDC cable, the microcontroller 35 notifies the EOT
processor which, in turn, causes status messages to be transmitted to the
HEU via the transceiver 32. Only after receiving the status message that the
EOT is connected and properly terminating the 230 VDC cable does the
1 ~ HEU cause the 230 VDC power to be turned on.
Once the 230 VDC power is turned on, the EOT continues to
function as an ECP EOT. The main piece of information that the ECP EOT -
needs and that the standard EOT has is the brake pipe pressure. The adapter
according to the invention communicates with the standard EOT via the
RS232 serial connection and extracts this information from the EOT
microprocessor.
Extreme reliability of the ECP EOT is an important aspect of the
invention. The reason is that an ECP train cannot operate without a working
ECP EOT. A failure of the ECP EOT function will result in a train stoppage
and then train operation below 30 MPH until the ECP EOT is fixed. Several
features have been incorporated into the ECP EOT adapter to address the
reliability aspect. These include the following:
Even if the EOT function fails and the ECP adapter cannot obtain
pressure information, the ECP EOT adapter continues in operation
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since the pressure itself is not a critical parameter in the sense that
the train can keep running even if the EOT pressure is not available
as long as the ECP EOT communication function can be maintained.
~ Battery failure will not affect the ECP EOT operation as long as
there is 230 VDC power. The diode 36 prevents a battery short
circuit from affecting the operation of the ECP EOT adapter.
Figure 4 is a flow chart illustrating the logic of the modified EOT
firmware. The process starts by either a standard battery pack or the ECP
adapter being plugged into the battery compartment of the EOT. Power to
10 the EOT microprocessor is turned on either by the act of plugging in the
standard battery pack or the ECP adapter or additionally turning on a power
switch. In either case, the EOT microprocessor goes through its usual power
up initialization in function block 41. Then, in decision block 42, the EOT
microprocessor determines whether it is to operate in the ECP mode. If not,
15 the firmware defaults to the standard two-way EOT processing in function
block 43. Even after defaulting to standard two-way EOT processing, if an
ECP mode command is received, as detected in decision block 44, the
process will loop back to decision block 42.
If the EOT microprocessor is to operate in the ECP mode, the
20 process goes to function block 45 where the radio transceiver in the EOT is
fumed offbut the marker light continues to operate. In addition, brake
pressure data is supplied to the adapter. A test is made in decision block 46
to determine if periodic ECP mode commands are being received from the
adapter. If so, the process continues to loop back to function block 45 to
25 maintain the EOT in ECP mode. If not, the process loops back to decision
block 42 to determine if the EOT should default to the standard two-way
EOT mode.
When in the ECP mode, the EOT microprocessor obtains a current
readings of the brake pipe pressure and transmits this data to the
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microcontroller 35 shown in Figure 3. A dedicated microprocessor in the,
microcontroller 35 formats a message including both the cable connection
status and the brake pipe pressure. The formatted message is then
transmitted by the microcontroller 35 for modulation and transmission on
the 230 VDC line by the neuron microprocessor 33 and transceiver 32.
Should continuity be broken, then no further status messages will be
formatted and transmitted to the HEU. In that case, a time out function at the
HEU would detect this condition and provide a warning to the engineer. It is
also possible to provide and additional function at the EOT which, when
10 continuity of the 230 VDC cable. is lost, will reactivate the radio
transceiver
of the EOT and transmit this information to the HEU.
The concept of a multifunction EOT is further enhanced by a
Universal EOT (UEOT). The UEOT monitors the train line and
automatically determines its mode of operation. Figure 5 is an elevation
view of the UEOT according to this aspect of the invention. This integrated
unit incorporates all the electronics and firmware to operate as a multi-
function EOT without need of an adapter. The UEOT is similar in
appearance to the standard EOT shown in Figure 1. A battery access door 19
covers the battery compartment. Built into the UEOT is a connector 22 for
making the connection to the ECP 230 VDC line.
Figure 6 is a block diagram of the electronics of the UEOT which is
similar to that shown in Figure 3 with the addition of the EOT electronics in
a unified package. The DC to DC converter 31 is a dual voltage. unit which
can be connected to a 230 VDC ECP train line or a 74 VDC non-ECP train
line. The converter 31, in either case, produces a 12 VDC output. In Figure
6, the EOT electronics includes a microprocessor control circuit 61 and a
nonvolatile memory 62 in which the control program for the microprocessor
controller and a unique identifier code of the particular UEOT are stored.
The microprocessor control circuit 61 also has inputs from a motion detector
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63, a manually activated arming switch 64 and a brake pressure responsive
transducer 65 and an output to an emergency brake control unit 66 coupled
to the brake pipe 67. The EOT electronics, when in the standard or
emulation modes, communicates via transceiver 68. In all modes, the EOT
5 electronics maintains the function of marker light 69.
The microprocessor driven control circuit 61 includes its own power
supply which receives power from the battery 34 and power from DC to DC
power converter 31. Thus, there is a built-in redundancy in the power
supplies to further enhance the reliability of the unit. This redundancy could
10 be omitted, with the consequential elimination of the reliability afforded
by
it, and the power for the microprocessor driven control circuit could be
solely derived from the power converter 37.
The transceiver 38 (Figure 3) is not needed in this integrated unit,
and communications between the microcontroller 35 and the microprocessor
15 driven control circuit 61 are via a direct microprocessor intemzpt. The
clock
input to the battery capacity meter 39 is supplied by the microprocessor
driven control circuit 61, and the data from the battery capacity meter 39 is
supplied to the microprocessor driven control circuit 61.
The UEOT man-machine operation remains the same as in the
20 standard EOT with the addition of an ECP status message. The operator
mounts the UEOT in a vertical position which powers on the EOT
processor. The microprocessor driven control circuit 61 sends a signal to the
microcontroller 35. The microcontroller 35 in turn powers on the "neuron"
microprocessor 33 and transceiver 32 which then "listens" for the HEU
beacon. If the UEOT "hears" the HEU beacon within a first predetermined
time period, it responds at a predetermined rate for a second predetermined
time period. If the HEU receives the EOT response during this second
predetermined time period, it applies the train line 230 VDC power. If the
UEOT does not "hear" the HEU beacon, the microcontroller 35 will power
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down the "neuron" microprocessor 33 for a predetermined period of time.
and then the power on/listen cycle will repeat. This is an optional power
saving technique.
The operator sees the marker activated for a predetermined period of
time, the brake pipe pressure displayed, and the ECP message displayed.
Standard arming procedure is initiated by an operator at the UEOT pushing
a testlarm button, and the engineer then can arm the UEOT for emergency
operation within a predetermined window. After this initial power on
sequence, the UEOT operates in one of three modes: standard, ECP, or 74V
10 emulation. The UEOT automatically switches to the appropriate mode of
operation as described below.
In the standard mode, the UEOT functions as a normal EOT with the
additional activation of the microcontroller 35 and periodic activation of the
"neuron" microprocessor 33 as described above to listen for HEU beacons.
While in the standard mode, EOT radio transmissions are sent to the HEU
periodically. The microprocessor driven control circuit 61 enters standard
mode upon power up and stays in standard mode until it receives a
predetermined sequence of messages within a predetermined period of time
from the microcontroller 35. This sequence of messages indicates HEU
beacons are being sent in ECP mode.
In the ECP mode, the UEOT provides ECP end-of train status
transmissions at a predetermined rate on the train line. These transmissions
contain the prescribed train line voltage, marker status, brake pipe pressure,
and battery capacity information from the EOT processor. The UEOT enters
the ECP mode when "neuron" microprocessor communications is
established with the HEU or when standard ECP level train line power is
turned on. The UEOT will continue in the ECP mode as long as train line
power is applied or HEU beacons are received. EOT radio transmissions to
the HEU are suspended as long as the EOT is in the ECP mode. The UEOT
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will return to standard mode if both the train line power and the HEU ,
beacons are not detected after a time interval. The return to standard mode
includes monitoring for train line power and cyclically monitoring for HEU
beacons. UEOT radio transmissions to the HEU begin again once the HEU
beacons cease.
In the 74V emulation mode, the UEOT monitors for failure
messages from the cars and relays these to the HEU via radio
communications. Entry into this mode may be controlled by either radio or
ECP commands from the HEU.
10 Figure 7 is a flow chart illustrating the logic of the UEOT firmware.
The process starts by a power up initialization in function block 71, which
occurs when the UEOT is mounted vertically. This initialization includes
powering on the microcontroller 35 and, in turn, the "neuron"
microprocessor 33. After power up initialization, the UEOT enters the
default standard mode in fimction block 72. A test is made in decision block
74 to determine if the UEOT hears the HEU beacon. If so, the UEOT
responds to the HEU via the transceiver 32 in function block 75 and enters
the ECP mode in function block 76. As described above, entering the ECP
mode includes (1) turning offthe radio transceiver, (2) maintaining marker
20 light function, and (3) sending pressure information via the
microcontroller
35 and transceiver 32.
While in the ECP mode, a series of tests are made to determine
whether the UEOT should remain in the ECP mode. The first of these in
decision block 77 is to determine whether HEU beacons are being received.
If so, the UEOT remains in the ECP mode. If no HEU beacons have been
received for a predeterniined period of time, a further test is made in
decision block 78 to determine if train line power in the range of 100 to 240
VDC is still being applied. If so, the UEOT remains in ECP mode. If no
HEU beacons are detected and sufficient train line power is not detected, a
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further test is made in decision block 79 to determine if a predetermined .
time interval has expired. If so, the process loops back to function block 72
.
where the UEOT again enters the default standard mode where a test is
made in decision block 74 to determine if HEU beacons are detected. If not,
5 a test is made in decision block 80 to determine if 74 VDC train line power
is detected. 74 VDC train line power is detected when power in the range of
30 to 100 VDC is detected. If not, the process loops back to function block
72; otherwise, the UEOT enters 74V emulation mode in function block 81.
The 74V emulation mode is for the case where the UEOT is
10 connected to a train not equipped with the 230 VDC ECP power. In this
mode, the UEOT takes its power from the train line but otherwise operates
in standard mode. While in the 74V emulation mode, the UEOT continues
to test the train line for 74 VDC train line power in decision block 82. If 74
VDC train line power is not detected for more than a predetermined period
15 of time as determined in decision block 83, the process loops back to
function block 72 where the UEOT again enters the default standard mode.
Combining the teachings of the first and second aspects of the
invention, an adapter can be provided which converts a standard EOT to a
UEOT. This adapter is mounted in the battery compartment of the standard
20 EOT, but instead of converting the standard EOT to an ECP EOT, the
adapter converts the standard EOT to a UEOT, providing all the
functionality of the UEOT as described above. The block diagram for the
UEOT adaptor is basically the same as that of the adaptor shown in Figure 3
with the difference in functionality being in the firmware of the adaptor. As
25 with the UEOT, the DC to DC converter 31 is a dual voltage unit which can
be connected to a 230 VDC ECP train line or a 74 VDC non-ECP train line
so that the 74V emulation mode is also supported by the adaptor.
Figure 8 is a flow chart showing the process implemented in the
UEOT adaptor. This process is essentially identical with that of UEOT as
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shown and described with respect to Figure 7 with the addition of decision
block 73 inserted between function block 72 and decision block 74. After
entering the default standard mode, a test is made in decision block 73 to
determine if any serial connection (e.g., RS232) ECP adaptor commands
5 have been received. This test is a test added for the purpose of
communication between the UEOT adaptor and the standard EOT
microprocessor via the transceiver 38 (Figure 3).
While the invention has been described in terms of preferred
embodiments, those skilled in the art will recognize that the invention can
10 be practiced with modification within the spirit and scope of the appended
claims.
TLK-97-OSCIP
