AM3270/TR3271 Reference Manual

Details of the PTP Protocol
AM3270 Subdevice Protocols
086705 Tandem Computers Incorporated 4–7
Table 4-1 lists some of the error conditions that could occur during READ and WRITE
operations.
Table 4-1. ITI Protocol READ/WRITE Errors
Operation/Error
Number
Description Action/Indication
READ 171 No response. The cluster controller for the
device did not respond.
Check the cluster controller for
an error condition.
READ 173 Text sent by the device was NAKed by
AM3270 until the retry count was exhausted.
Generally indicates some part of
the communication system (line
and modem) is not working
properly.
READ 177 Text Overrun. The READ request count
specified was smaller than the actual text size
received from the device.
Increase the READ count.
WRITE 123 Device Busy. For a CRT, indicates that the
terminal operator is doing an operation that
has locked out the device to any WRITE
operations.
Retry the WRITE operation from
the application process.
WRITE 171 No Response. When the device was
selected, the cluster controller did not
respond.
Same as READ 171.
WRITE 172 Improper Reply. The selected device
responded with an invalid control sequence.
Generally indicates a 3270
problem or a sequence of
problems with the
communications system.
WRITE 173 Text sent to the device was NAKed by the
device for the retry count.
Same as READ 173.
WRITE 179 Incorrect Buffer. The text buffer sent to the
device contains invalid 3270 orders.
Generally indicates an application
programming problem.
The text buffer must be analyzed
for incorrect data.
WRITE 180 Unknown device status received. An invalid 3270 device status
was received and could not be
translated into a usable error
number. Use SCF to determine
the status received.
Details of the PTP
Protocol
The PTP protocol provides the ability to interconnect an AM3270 subdevice directly to
a TR3271 subdevice without an intervening application process. This capability is
normally used to attach certain subdevices controlled by AM3270 directly to a host
system.
Figure 4-2 illustrates a typical pass-through configuration.