Wait on an ECB

Program-to-Program Interface › Wait on an ECB

Wait on an ECB

To allow the caller to wait on an ECB, use request code 24. This request code allows receiver programs written in languages that do not support a WAIT service to wait for input.

The RPB fields in the following table must be set up before the call:

Bytes	Field Name	Set to...
00–03	RPLEN	56.
04–05	REQUEST	24.
12–15	WORKADDR	The address of a 128-byte work area.
20–23	ECBADDR	The address of the ECB.

The RPB field in the following table is returned after the call:

Bytes	Field Name	Set to...
08–11	RETCODE	The return code.

The following return codes are possible:

0: Request completed successfully—the ECB has been posted.
18: The ECB was not 0 on entry to this function—it might have been already posted.
22: The requestor is not in primary addressing mode.
24: PPI is not active.
28: PPI requests are not supported.

Important! Use this function only if your programming language does not support a WAIT facility. Unpredictable results can occur if the PPI subsystem is terminated while you are waiting using this request.

The ECB address is returned by a request code 4 (define a receiver).

You can wait using request code 24 after receiving a return code 30 from receive.

Remember to test the ECB post code in the last byte of the ECB for 0 (data available) or 99 (PPI shutting down).