GE GFK-1541B manual Communications Status Words, Format of the Commreq Status Word CRS Word

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Communications Status Words

The COMMREQ Status word (CRS word) and the first word of the two Detailed Channel Status words (DCS words) report status and errors in the same format, as shown below. 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 contents 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:

ƒThe Ethernet Interface is powered up or restarted

ƒThe CPU transitions from STOP to RUN

ƒA channel abort COMMREQ aborts the channel

Format of the COMMREQ Status Word (CRS Word)

CRS Word in

Hex Format

High Low

00 00

Minor Error Codes (high byte)

Success and Major Error Codes (low byte)

Format of the Detailed Channel Status Words (DCS Words)

DCS Word in Hex Format

		Word 2	Word 1
			High	Low
	0000		00	00
Channel Active (0001 = channel active,
0000 = channel not active)

Minor Error Codes (high byte)

Success and Major Error Codes (low byte)

There are several points to remember when interpreting the contents of the COMMREQ 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.

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 the COMMREQ function and then check for a non-zero value indicating that the Ethernet Interface is responding to the COMMREQ. A good way to do this is to use a MOVE WORD function block to zero the CRS word.

3-36 TCP/IP Ethernet Communications for the Series 90™ PLC User's Manual– May 2002 GFK-1541B