GE GFK-1004B Manual Do Utilizador
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GFK-1004B
Chapter 4 Programming Communications Requests
Communications Status Words
The COMMREQ Status word (CRS word) and the first word of the two Detailed Chan-
nel Status words (DCS words) report status and errors in the same format, as shown be-
low. The second word of the DCS words indicates when the channel is active.
nel Status words (DCS words) report status and errors in the same format, as shown be-
low. The second word of the DCS words indicates when the channel is active.
The CRS word location is specified in Words 3 and 4 of the Command Block. The DCS
words location is specified in the Retrieve Detailed Channel Status Command. The con-
tents of these status words are defined below:
words location is specified in the Retrieve Detailed Channel Status Command. The con-
tents of these status words are defined below:
The initial value of the Detailed Channel Status words is all zeros. DCS words are reset
to zero when:
H The Ethernet Interface is powered up or restarted
to zero when:
H The Ethernet Interface is powered up or restarted
H The CPU transitions from STOP to RUN
H A channel abort COMMREQ aborts the channel
Hex Format
High
Low
00
00
Minor Error Codes (high byte)
Success and Major Error Codes (low byte)
CRS Word in
Figure 4-3. Format of the COMMREQ Status Word (CRS Word)
High
Low
00
00
Minor Error Codes (high byte)
Success and Major Error Codes (low byte)
0000
Channel Active (0001 = channel active,
0000 = channel not active)
DCS Word in Hex Format
Word 1
Word 2
Figure 4-4. Format of the Detailed Channel Status Words (DCS Words)
There are several points to remember when interpreting the contents of the COMMREQ
Status word and Word 1 of the Detailed Channel Status words:
Status word and Word 1 of the Detailed Channel Status words:
1.
Display the Status Words in hexadecimal form to more easily differentiate the high and
low bytes. A good way to do this is to use a MOVE WORD function block to display
the hexadecimal value within the ladder program.
low bytes. A good way to do this is to use a MOVE WORD function block to display
the hexadecimal value within the ladder program.
2.
The Ethernet Interface will never send a zero for the COMMREQ Status word to the
PLC CPU. The user program should zero the COMMREQ Status word before issuing
PLC CPU. The user program should zero the COMMREQ Status word before issuing