Note: Descriptions are shown in the official language in which they were submitted.
2070~9~
.` 1
DYNAMIC ASSOCIATION OF RF RADIO DATA
C(~MMUNICATION SYSrEM IN A PRE-E~ISIING COMPUIER
CONT~OL~NEIWOE~;K
Background of the Invention
This invention relates generally to RF Radio Communication
Systems and, in particular, to such systems having a capability of
interfacing within an e~sting, standardized computer controlled
10 communication network of linked controllers and fLsed tenninal
devices operating on a pre-established protocol.
Computer control communication networks are of cour~e
known in the art. Typically, such systems utilize one or more cluster
15 controllers interfacing with a plurality of individual terminal
devices, all controlled by a ho~t computer.
One such communication network, for purpoaes of illustration
and by way of example only, is the IBM 3270 system which is
20 recognized as a standard in the industry. The 3270 system employs a
Host Computer which includes one or more Logic Units (LU)
interfacing to one or more associated 3274 Cluster Controllers, which
in turn control a plurality of fixed terminal devices, such as a 3274
Display Terminal or a 3278 Line Printer. The IBM 3270 system
25 operates with a ~tandard operating protocol, also well known in the
industry.
Accordingly, it will be appreciated that where an RF Radio
-Data Communications System is to be establi~hed, the Radio Data
30 System may operate with some arrangement of pre-estaWshed but
typically different operating protocol, which then may or may not
require a separate host computer. In any event, appropriate
progr~mming must be effected to accommodate the particular
operahng protocol beir g utilized.
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207~9~6
If, on the other hand, the RF Radio Data Communication
System can operate with, or at least emulate that of the pre-
established computer controlled fi~ced communications network, say,
5 for example, the referenced IBM 3270 system, the RF Radio Data
Communications System can be made to interface with the host
computer as one or more 3274 cluster controllers which in turn
control a plurality of radio data portable terminals emulating either a
3278 fi~ed display or a 3287 Line Printer. "Portable" i8 used to
10 designate either a portable or mobile unit, and distinguish the same
firom a fixed terminal unit. In any event, the portable radio
terminals may be programmed to redefine its keyboard and display
output to simulate in all respects a 3278 fixed terminal device.
Similarly, the portable radio terminal may connect to an optional
15 printer device and then be programmed to simulate the IBM 3287 line
printer. No reprogramming of the host computer i8 then necessary
because all of the end terminal devices, fixed or portable, look like a
3270 device operating with standardized protocol being employed
within the particular IBM 3270 computer controlled com~unication3
aD network.
There remains still one other consideration to be taken into
account. First, without more, each of the portable radio data
terminals in ru~niDg the 3270 emulation package, will appear to the
25 system controller as a single f~ced terminal device. As such, it
occupies one of the available links to the controller in the same way
as any other lilce f~ed terminal di~play device. However, this could
very likely necessarily prove wasteful since the radio data 3ystem
po~table data terminals are normally not all active, at least not all at
3û once, but only occasionally, and on a selective basis. Moreover, if any
particular link or controller fails, the portable data terminal
assigned thereto would be cut off and unable to communicate with
the host computer.
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`` 2070996
Summary of the Invention
Accordingly, it i8 an object of the present invention to provide
an RF Radio Data Communication system that emulates a
5 component part of a known computer-controlled communications
network and operates to interface with a host computer as one or
more cluster controllers and in this fashion functions to effectively
overcome the foregoing deficiencies.
A more particular object of the present invention is to pro~ide
and RF Radio Data Communication System of the foregoing type
wherein the system portable radio data terminals emulate a known
and fully compatiUe f~ed tenninal display device, but the number of
such emulating portable device~ may be ma~cimized by being shared
15 between a number of available cluster controller links.
Still another object of the present invention is to provide an RF
Radio Data Communication System of the foregoing type wherein the
sharing of the portable Radio Data terminals is effected by the
20 association thereof with a pool (hunt group) of selected controller link
devices.
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In practicing the invention, an RF Radio Data Communication
System is provided which is capable of interfacing as a plurality of
25 controller li~s to a host computer in a computer controlled
communications networ} of controlled terminal devices operating
with a given, i.e., standardized, operating protocol. A network
control processor (NCP) is interconnected to at least one of a plurality
of logic units included in a host computer which supports a given
30 number of LU sessions with each of ~aid interconnected host
computer logic units. Further, a plurality of portable rsdio terminals
intended for operation within the RF Data Communication System
are provided wherein each such terminals are adapt~d to emulate a
compatible f~sed terminal display normally operating in the
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207099~
controlled communication networlc with the standardized operating
protocol. Further, the portable radio terminals are each auociated
with a defined hunt group comprised of a plurality of LU session~
from the given number of LU se~ion~ available, and wherein such
5 portable radio terminals rnay freely contend for an a~ailable LU
session ~n its assigned hunt group. And finally, wherein there are a
greater number of portable radio tata brminals associabd with the
hunt group than there are LU sessions.
Brief Description of the Drawings
The features of the present invention which are believed to be
novel are set forth with particularity in the appended claims. The
invention itself, however, together with further objects and
15 inventions thereof, may be best understood by reference to the
accompanying drawings, in which:
Fig. 1 i8 a block diagram of a typical computer-controlled
communication network, in this case, the IBM 3270 system;
Fig. 2 is a block diagram of a typical RF Radio Data
Communication System controlled by an associated host computer;
~ Fig. 3 is a bloc} diagram of an RF Radio Data Communication
- ~ 25 System similar to that of Fig. 2, but in which the infrastructure
inbrfaces with the host computer as a plurality of cluster controllers
and in which portable radio data brminal~ emulab a fised terminal
device, as in accordance with the present invention;
Fig. 4 is a partial bloc} diagram showing a plurality of portable
radio data terminals of the system of Fig. 3 either dynamically or
statically associated with an assigned LU session;
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Fig. 5 is graphic representation of a series of hunt groups
fo~ned by indi~idual portable radio data terminals associated
therewith;
Fig. 6 is a flow chart indicating the initialization proeedure in
which a given portable radio data terminal may as~ociate with a
particular LU session;
Fig. 7 is flow ehart of the procedure followed by the network
lD control proeessor (NCP) upon reeeiving an inbound message from a
portable radio terminal;
Fig. 8 is a flow ehart indicating the background actions
periodically effeeted by the NCP regarding the dynamic association of
e systems' portable radio data terminals; and
Fig. 9 is a flow ehart indieating the action tsken by the NCP
npon ho~t linl~ failure.
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Description of the preferred Embodiment
R~ferring now to the drawings, a typical computer-controlled
5 communication network iB shown at 10 in Fig. 1. In this instance,
for purposes of example only, the network is shown as an IBM 3270
System, well known in the art wherein a host computer 12 is provided
which interfaces with a plur~ity of 3274 Cluster Controllers 14,
which in turn interface with and control individual 3278 Display
10 Terminal Devices 16. The later could be substituted with 3287 Line
Printer Devices, as des*ed. Network 10 operates with a known, pre-
established operating protocol, the details of which may not be
described in detail for purpo~es of the present invention.
Similarly, an RF Radio Communications System or network is
indicated at 20 in Fig. 2, which network may likewise be con~idered
a~ typical of those known in the art. As shown, sy~tem 20 includes a
Network Control Processor (NCP) 22 interfacing with a Host
Computer 24 and controlling in response thereto a plurality of RF
ao Stations 26 at various locations, each of which comprise an RF
Modem 28 a Transmitter 30, and a Receiver 32. Station 26 then
communicates over antenna 34 with a plurality of portable radio data
ter~unals 40.
System 20 conventionally operates over inbound and outbound
communications channels on a contention basis in accordance with
an established operating protocol, such as that referenced in US
Patent Application. Serial No. 07/175,888, filed 31 March 1988 on
behalf of Kenneth J. Zdunek, et al, and assigned to the same a~signee
as the present invention. For purposes of brevity, such operating
protocol may be referenced to as Motorola MDC 4800 operating
protocol.
207~99~
As referenced in the 07/176,888 Zdunek Patent Application,
remote data terminals transmit data messages to the Host Computer
(~ria the NCP) in the form of data packets by RF link over the inbound
channel~ and receive like messages therefrom over the outbound
5 channel. A Carrier Sense Multiple Access (CSMA) technique is
utilized, which is of course well known in the art.
As will be appreciated, the messages sent to the associated
system remote data terminals originate at the Host Computer, and it
10 is to the Host Computer that the remote terminals remotely
communicate with in sending inbound messages. Without more,
such an arrangement requires a dedicated Host Computer operating
with the above-referenced protocol procedures. However, if a u~er
already has a pre-e isting Computer Controlled Network in which a
15 Host Computer is included, and if available capacity is present, a
radio data networlc can be added to such computer network, if, but
only if, such radio data network can be made to emulate one or more
cluster controllers already operating in such computer network
system. For esample, if the Radio Data Network 20 in Fig. 2 can be
20 made to emulate one or more 3274 Cluster Controllers as referenced
in the e~amph of Fig. 1, the result i8 the overall system 100 as set
forth in Fig. 3, which system has been constructed in accordance
with the present invention.
26 As therein indicated, the Radio Data System 20' is linked to the
Host Computer 12 of Computer Controlled Network 10' by a plurality
of direct coDnections 102a, 102b and 102c. In this instance, however,
the RF radio data infrastructure is made to emulate a plurality of
3274 cluster controllers and in this manner, no change in the
operating protocol is necessary as far as the Host Computer 12 is
concerned. Each of the direct line connections 102a, 102b and 102c
looks like a 3274 Cluster Controller, each of which presents a
plurality of LU Sessions (typically about 32 in number~.
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In this fashion, the full RF Radio Data System 20' may operate
as usual, but in the Computer Controlled Networlc 10', and the Host
computer 12 accommodates both system 20' a~ well as the various
Cluster Controllers 14. However, it will be appreciated that, without
5 more, each LU Session presented through line connections 102a, 102b
and 102c would interface with an associated terminal unit (terminal
session) on a one-to-one basis. Since not all of the system Radio Data
Terminals are active at the same time, it would otherwise represent
a less than efficient use of available resources. Moreover, if any of
lD the LU Sessions (emulating a cluster 3274 controller) fails, the Radio
Data Terminals permanently interfaced to such LU Session would
thereby be cut off and denied communications access and capability.
Accordingly, the present invention provides an advantageous
15 enhancement to the aforementioned 3270 emulation protocol whereby
substantially increased numbers of radio data terminals may be
incorporated into the system. Also, a redundancy feature is provided
to cover the drop out of any emulated 3274 Cluster Controllers and LU
Session failure. ~nd, finally, such enhancement efflctively
20 minimizes the total number of 3270 LU &ssions that may in fact be
required in a particular system.
To accomplish these and other objectives, each of the Radio
Data Terminals 40 are selectively associated with a particular Hunt
25 Group. Fig. 5 illustrates this feature. Conceptually, there are no
limits to the number of data terminals that can in fact be associated
with a Hunt Group. In practical terms, however, there are of course
limits. The key criteria in this event is that all such data terminals
associated with a particular Hunt Group must be of the same 1 ype.
30 For essentially arbitrary reasons, but consistent with (IBM) protocol
and architectural guidelines, type 2 is designated for conventional
(3278) terminals and type 3 for (3287) printers.
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Similarly, each of the LU Sessions with the Host Computer
(thru a link controller) are associated with a select Hunt Group. As
indicated in Fig. 5, neither the group of data terminals constituting a
particular terminal session, nor the LU Sessions from a particular
5 emulated 3274 linlc controller, are limited to only one Hunt Group. In
fact, they are to be disbursed, as indicated specifically in Fig. 5. As
shown, and by way of e~ample only, Terminals 1 through 4, of
terminal session 1, are associated with Hunt Groups in thi~ case, a
type 2 LU. As will also be noted, terminal 6 of session 1, is indicated
10 as associated with Hunt Group 2 a LU type 3 accommodating 3287
printers. Further, terminals 7 and 8 of session 1 are indicated as
associated with Hunt Group 3 while terminal 9 et seq. are associated
with Hunt Group N.
Similarly, a portion of the available LU Sessions of 3274 Host
Link 1 are associated with Hunt Group 1 while others may be
associated with still different Hunt Groups, such as those shown
interfacing with Hunt Group 2. Host Link 2 LU Sessions are shown
selectively interfacing with Hunt Groups 2, 3 and 4. In this selective
20 manner, it will be readily appreciated that a greater number of Data
Terminals 40 can be associated with a lesser number of available LU
Sessions through a particular Hunt Group. Moreover, since the LU
Sessions of a par~icular emulated Link Controller are associated with
one or more Hunt Group, a failure of that Link Controller simply
26 means communications are rerouted through a different Link
Controller, thereby providing the very important redundancy feature.
This is made possible by the adaptable linking of the terminals to a
particular LU &saion (through a particular Hunt Group). Thi~
linking may be dynamic, as through a particular Hunt Group (to any
30 one of a number of value sessions), or static (as always as~ociated
with a specific one), a8 best seen in Fig. 4.
AB therein shown, a terminal session is considered strongly
linked (dynamically) to an LU Session once such session is
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successfillly logged on. As previously stated, a static linking always
require~ a particular data terminal to be associated with a predefined
LU Session. as graphically portrayed in Fig. 4.
Given the LU association~ as described above, the flow chart
represented by Fig. 6 indicates the particularized actions effected on
each 3274 LU initialization request. At the start, the inquiry is made
as to whether the LU is static as indicated in step 120. If yes, the LU
is strongly linked to a terminal session and may proceed accordingly
as indicated at step 122. If, however, tbe answer that the LU i~ not
static, it by definition must be dynamic as indicated at step 124.
Ihereupon the further inquiry is made at step 126 as to wbether the
LU is weakly or strongly linked to a terminal session. If yes, the
process continues with the lin~ed terminal session at step 128 and if
tenninal session is logged in at step 130, a strong terminal link is
e~ected between that tenninal session and the referenced LU as
indicated at 132. If the terminal session is not logged in, it ~imply
returns to the same condition as at the beginI~ing of the initialization
process. Further, if the LU is weakly linked to a terminal ses~ion as
indicated at step 126, the LU is added to the list of available LUs for
the associated Hunt Group as indicated at Btep 134 whereupon the LU
initialization process may be terminated.
From the remote data terminal ~iewpoint, Fig. 7 represents a
26 flow chart of the e~ecuted actions occurring upon the Network
Control Processor 22 receiving inbound terminal messages. As
indicated, the initial query at step 140 is as to whether the terminal
session is static. If yes, the message is then forwarded to the linlced
LU at step 142 whereupon the process i8 completed at that point. If,
however, the answer is that the terminal session i8 not static, then it
must be dynamic as indicated at step 142 and the further query is
made at step 144 as to whether the terminal session is weakly of
strongly linked to a LU. If strongly linked, the message i8 forwarded
to the linked LU at step 146. If the terminal session i8 logged in at
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11 207~96
step 148, it is strongly linked to this LU as indicated at step 150. If,
however, the terminal session does not log in, it terminate~ and the
LU initialization process will reactivate subsequently. If, on the
other hand, the terminal session is weskly linked to an LU, the
5 further query is mate at step 152 a8 to whether the LU is available in
this terminsl's Hunt Group. If in the negative, an intication is
returned to terminate this session because the host is not available a8
inticatet in step 154. If on the other hand, a LU iB available in the
particular Hunt Group, the LU is removed at step 156 from the list of
10 available LUs for that Hunt Group, whereupon the terminal session
is weakly linked to this particular LU as indicated at step 158. The
message is forwarded to the weakly linked LU at step 160 and, if the
terminal session i8 static, the message is forwarded to the linked LU.
If not, the process will terminate at this point.
Fig. 8 illustrates in flow chart form the background actions
eYecuted by the network control processor 22 for dynamic LUs while
Fig. 9 illustrates in flow chart form the actions esecuted by such
network controller upon 3274 Host Link failure~ In Fig. 8 the
20 controller 22 delays for the specific delay inten~al as indicated at step
180 and then scans weakly linked LUs for those that have not
processed traffic from their terminal session in a weak time out
interval, as indicated at step 182. Accordingly, for those found, the
- temporary terminal session link i~ removed and the LU i8 returned
25 to the list of available LUs for the appropriate Hunt Group as
~, indicated in step 184~
In Fig~ 9 step 190 indicates that all failed 3274 LUs are
; removed from all associated Hunt Groups and, further, that all
33 terminal to LU session linkage~ are likewise broken for the failed
3274 LUs, as shown at step 192~ In this manner, the as~ociated data
terminals that would otherwise be locked out of its ability to
- communicate may be reas~igned to visble Hunt Groups and working
;~ 3274 Link Controllers~ This redundancy feature is therefore
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significant in in~uring communication linkages with all
communication capable radio data terminal~.
Accordingly, What is Claimed i8:
