ACC Programmer's Reference Guide

ZCOM Tables and Data Structures
Message Header
Chapter 3116
MTAGW1, MTAGW2 - Message tag words
These are application defined tag words that are passed unaltered
through the ZCOM subsystem with the message data. They are supplied
in the zsend and zcntl calls and returned in the zread call. When a
receive message is returned from a terminal, the tag words are set to
zero.
MZAUXL - Auxiliary ZCOM address
When using the multiplexed mode of operation through the logical
terminal table, this field stores the original source ZLU.
Message Request Header (zmrq_type)
The six-byte message request block may or may not be present,
depending on the message type and whether it is destined for a terminal.
For request types 1, 4, and 6, to a terminal, the request block will be
present; for request types 2 and 7 the request block will contain
meaningless data. More information on the contents of this block can be
found in the firmware reference manual. The Message Request Header is
always present. For message types 2, 3, 7, 10, 11, and 15, it contains
meaningless data. For types 4, 6, 12, and 14, it contains valid data.
MRQCODE - Terminal request code
Table 3-38 Message Request Header (zmrq_type)
Field Name Field Description Field Type
Size
(Bytes)
MRQCODE Request code uns.char 1
MRQTERM Terminal number uns.char 1
MRQSTAT Request status uns.char 1
MRQTAG Tag parameter uns.char 1
MRQLEN Data length uns.short 2