AM3270/TR3271 Reference Manual

Details of the ITI Protocol
AM3270 Subdevice Protocols
086705 Tandem Computers Incorporated 4–3
CONTROL 11 and 12
(Modem Connect or
Disconnect)
The CONTROL procedure performs device-dependent I/O operations. A CONTROL
11 means wait for modem connect; a CONTROL 12 means disconnect the modem.
Even though a CONTROL 11 or 12 is meant for use in a dial line environment, note
that dial lines are not supported in AM3270. However, as stated in the beginning of
this section, the primary usage of the ITI protocol is to allow a 3270-family terminal to
run a Tandem command interpreter.
The command interpreter does make use of the CONTROL procedure with a function
code of 11 or 12. To ease the impact on application programs, a CONTROL 11 or 12
that is issued to this protocol results in an error-free return, but no action is performed
by AM3270. No error is returned. If a CONTROL procedure is issued with any other
function code, it is rejected by the protocol and an error 2 is returned (invalid
operation).
CALL CONTROL (filenumber, operation, parameter [, tag ])
filenumber
is the file number provided by OPEN (INT:value).
operation
an INT:value 11 = wait for modem connect , 12 = disconnect the modem
parameter
usually an INT:value (in this instance, nothing is defined).
tag
an INT(32):value for nowait opens; optional parameter.
READ Request A READ request causes the subdevice to be added to the poll list. When the device
responds with text, the blocks received by AM3270 are collected and stripped of any
communication control characters. When the final block is received, the READ is
completed to the application process with pure text only.
Status messages sent by a device are not passed to the application, but are evaluated
and the READ is completed with a file system error number, if appropriate.
SETMODE 53 (status receipt) is not supported for this protocol.
SETMODE Functions The call to SETMODE is as follows:
CALL SETMODE (filenumber, function, [, parameter 1 ]
[, parameter 2 ] [, lastparams ])