Rockwell Automation 57C442 Data Highway Plus Interface Module - Manual (Page 30)

4-12
For the commands shown in figure 4.6, both logical binary and logical
ASCII addresses are supported.
The Diagnostic Read command returns the values for counters as
shown in Appendix G. The Diagnostic Status command returns 17
bytes containing the following information:
The commands shown in figure 4.9 write directly to or read directly from
file N7 on the module. The address field is used as an offset into the
file. If the address does not exist, an error is returned.
Unprotected writes will be processed in the same manner as Protected
writes and will not be permitted to store data in the protected areas of
the PLC-5 image in the dual port memory.
Command Function Description
06 07 Diagnostic Counters Reset
06 01 Diagnostic Read
06 03 Diagnostic Status
Figure 4.7 – Privileged Commands in the Basic Command Set
Byte Value Meaning
1 FE Terminal
2 1B Terminal
3 A3 Module identifier
4 Active station list pointer low byte
5 Active station list pointer high byte
6 Diagnostic counters pointer low byte
7 Diagnostic counters pointer high byte
8 Reserved
9 Reserved
10-17 Terminal name (automatically padded with blanks)
Figure 4.8 – Diagnostic Status Command Data
Byte Value Meaning
02 n/a Protected Bit Write
00 n/a Protected Write
05 n/a Unprotected Bit Write
01 n/a Unprotected Read
08 n/a Unprotected Write
Figure 4.9 – Non-Privileged Commands in the Basic Command Set