Processors with a built-in Fipio link can be used to simultaneously activate 24 explicit exchange functions.

An exchange request sent to a Fipio device can take several MAST task cycles. It is therefore essential to manage the words of the exchange management parameters for every explicit variable exchange, including READ_STS(IODDT_VAR1) and READ_STS(IODDT_VAR2). This requires IODDT-type IODDT_VAR1 and IODDT_VAR2.

If for example 24 functions are being processed simultaneously, or if 25 functions are triggered in a same task cycle, then all new functions (or the 25th) will not be served and will end in error.

For a READ_STS exchange, given that the 25th exchange is not possible, the report raises a communication fault in word %MW\2.e\0.m.c.2

For exchanges WRITE_CMD, READ_PARAM, WRITE_PARAM, RESTORE_PARAM, the report raises a communication fault in word %MW\2.e\0.m.c.1. A probable cause is the lack of system resources to provide the service.

System word %SW155 contains the number of explicit exchanges in progress. Bit %SW116 .2 switches to 1 if the maximum number of simultaneous explicit exchanges is reached or exceeded.