AM3270/TR3271 Reference Manual

Level 4 Protocols
Overview of AM3270 and TR3271
2–2 086705 Tandem Computers Incorporated
Note PTP is a trademark of Tandem Computers Incorporated. CICS is a trademark of IBM Corporation. CICS,
when used in this manual, refers to products, technologies, architectures, processes, standards, or APIs
originated by IBM Corporation. The term “CICS server” or “CICS application,” for example, when used in
this manual, refers to a server or an application that will interoperate with an IBM API. The PTP Services
product is compatible with applications for IBM Corporation’s CICS™ products.
With TR3271 a Tandem application program appears to be a terminal to the IBM host.
Specifically, the application can act as one or more individual 3270-type terminals or
printers connected to a byte-synchronous multipoint communication line.
TR3271 may be used in three different ways:
With application programs acting as one or more 327x terminals or 328x printers
Programmed pass-through. With this method, application program(s) can open
both TR3271 and AM3270 devices and can perform routing functions, depending
on data input at the terminal.
Pure pass-through. Subdevices in this mode use the pass-through-protocol (PTP)
which logically connects them with AM3270 subdevices.
When used together with the AM3270 pass-through protocol TR3271 allows actual
3270 devices to:
connect to a Tandem system, and
access application programs running on an IBM system connected to any Tandem
system on an Expand network.
List of Supported IBM CUs These are some examples of the IBM control units (and equivalents) that are currently
supported:
3271, Models 1 and 2
3274, Models x1C, 3174
3275, Models 1 and 2
3276, Models 1, 2, 3, and 4
Subsystem Components The AM3270 and TR3271 access methods are used with 3650/6100 communications
subsystems (CSS), including the 3605/6105, that have the following components:
the line
the Tandem host
the CSS, with its own AM3270 and TR3271 CLIP code
the I/O processes
the cluster controller (optional)
the various subdevices
Level 4 Protocols Using the Subsystem Control Facility (SCF), individual terminals and printers can be
configured as subdevices using the following protocols.
Interactive terminal interface (ITI) protocol
Pass-through protocol (PTP) mode