Programming the Local Host
Chapter 5
521
Immediately before it sets a remote or local fault bit ON, the PLC-2/DHII
interface enters a four-digit error code into the error code storage word.
The error code storage word is described in the discussion on “Error
Word.”
By monitoring fault bits in the program, operator personnel can be alerted
to hardware conditions which prevent normal transmission and execution
of commands. (Programming techniques for monitoring fault bits are
described in the discussion about “Initiating and Monitoring Commands.”
Error Word
When the PLC-2/DHII interface cannot carry out a command due to a
programming error or a discrepancy in data, it writes an error code into
the error word you select in the header rung of the communication zone.
This word stores the most recent error code written by the PLC-2/DHII
interface.
Figure 5.13 shows the structure of the error word. The lower byte of this
word (Bits 00-07) stores any error code entered by the PLC-2/DHII
interface. In this byte the error code is represented as a two-digit
hexadecimal number.
Figure 5.13
Error Code Word Format
17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
TwoDigit Value:
Reference Number (for Codes D2E7 Hex)
Counter (for Codes 10CF Hex)
Hex Count
Error Codes 00FF
Hex Format
(Refer to Appendix B)
0 F
0 F
0 F
0 F
