Emerson PACSystems RX3i - Page 156

PACSystems™ RX3i and RSTi-EP CPU Reference Manual Section 6
GFK-2222AK October 2019
Serial I/O, SNP & RTU Protocols 148
2. A write request was initiated previously and transmission of the specified number of
characters is complete or a time-out has elapsed.
The status returned by the function indicates the event or events that have completed.
More than one condition can occur simultaneously, if both a read and a write were
initiated previously.
6.2.9.1 Example Command Block for the Read Port Status Function
VALUE
(decimal)
VALUE
(hexadecimal)
MEANING
Address
0003
0003
Data block length
Address +1
0000
0000
NOWAIT mode
Address +2
0008
0008
Status word memory type (%R)
Address +3
0000
0000
Status word address minus 1 (%R0001)
Address +4
0000
0000
Not used
Address +5
0000
0000
Not used
Address +6
4303
10CF
Read port status command
Address +7
0076
004C
Port status memory type (%M)
Address +8
0101
0065
Port status memory offset (%M101)
6.2.9.2 Port Status
The port status consists of a status word and the number of characters in the input buffer
that have not been retrieved by the application (characters which have been received and
are available).
word 1
Port status word (see below)
word 2
Characters available in the input buffer