Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 User Manual
Page 148
Binary Command Language
Appendix A
A-20
The following example command block uses the read I/O word command
to request the data and force information for the output word representing
rack 6, module group 4:
STX
02
ISC
01
SIZ
03
CMD
23
34
DAT
00
ETX
03
CHK
60
The data bytes store:
lower byte of the I/O address (34 hex)
upper byte of the I/O address (00 hex)
The processor responds to a read I/O word command with one of the
following response codes:
Response Codes
Hex
Description
00
Success
03
Forces unavailable
04
Address unknown
06
Access not allowed
08
Address not complete
When the processor returns a success response, the data buffer also
contains the data stored at the requested address, and force-on and
force-off masks associated with that data. The following example shows a
response block for a read I/O word command when forces exist:
STX
02
OSC
01
SIZ
07
RSP
00
61
1C
02
CHK
92
DAT
86
80
00
ETX
03
The data bytes store:
lower byte of the data word (61 hex)
upper byte of the data word (1C hex)
lower byte of the force-on mask (02 hex)
upper byte of the force-on mask (86 hex)
lower byte of the force-off mask (80 hex)
upper byte of the force-off mask (00 hex)