Envoy ACP/XF Application Programming Manual

EnvoyACP/XF and the Application Task
EnvoyACP/XF Application Programming Manual–132179
1-7
Setting Line-Configuration Parameters
Setting Line-Configuration Parameters
Line-configuration parameters specify the following characteristics:
•
Type of line (full-duplex or half-duplex)
•
Type of local station (primary, secondary, or combined)
•
Type of connection (switched or nonswitched)
•
Type of electrical interface (RS-232 or RS-422)
•
Polling interval (for NRM)
•
T1 timer (for ABM)
•
Window size
•
Maximum frame size
•
Size of control field
•
Size of address field
•
Translation (EBCDIC)
•
Line statistics threshold
•
Number of retries (attempts to send a message after an error occurs)
You usually set these line-configuration parameters during system configuration (see the
EnvoyACP/XF Configuration Manual). If you wish, you can alter these parameters
dynamically using the SETMODE or SETMODENOWAIT procedure. These calls
include numerical function codes which set different line-configuration parameters (see
SETMODE Function Codes
on page 4-15 for details). Even when your application is not
overriding the configured parameters, you should use one or more SETMODE or
SETMODENOWAIT calls. These calls ensure that the parameters for the application
program are properly set.
The use of waited I/O restricts you to the SETMODE procedure. The use of nowait I/O
enables you to call either SETMODE or SETMODENOWAIT. Any attempt to issue
either of the above calls while another nowait operation is outstanding results in file-
system error 27. However, if you do a SETMODENOWAIT, the application can send
READs or WRITEs before the SETMODENOWAIT is completed. The READs or
WRITEs will queue until the SETMODENOWAIT completes.
The SETMODE 30 procedure is particularly useful in two-way simultaneous (TWS)
operation. It allows nowait I/O operations to complete on the application level in the
order in which they are completed by the I/O process.
If you use SETMODE 30 with multiple line openings and use each opening for both
READ and WRITE commands, you must issue a SETMODE 30 call to each line
opening. This is the only instance in which you must issue a SETMODE call to more
than one opening of a line.