3

Retrieve Detailed Channel Status (2002)

The Retrieve Detailed Channel Status command requests that the current Detailed Channel Status words be returned for a channel. The Detailed Channel Status words contain an active/inactive channel indicator and the last channel error codes seen. These two words of detailed status supplement the information available in the COMMREQ Status word and the Channel Status bits. The command has no effect on the value of the Channel Status bits.

Be aware that the Detailed Channel Status words are updated every time the status of the channel changes. If, for example, the channel is operating with a fast repetition period, the status words may change faster than the ladder executes the COMMREQ to retrieve them. Therefore, some status values might be missed from the ladder’s point of view.

Example Command Block

Retrieve detailed channel status for Channel 5. Store the Detailed Channel Status words to Registers %R100–%R101. Return the COMMREQ Status word to %R10.

 

 

Dec

(Hex)

 

 

Word 1

00004

(0004)

Length of Channel command Data Block (4 words)

 

Word 2

00000

(0000)

Always 0 (no-wait mode request)

 

Word 3

00008

(0008)

Memory Type of CRS word (%R)

 

Word 4

00009

(0009)

CRS word address minus 1 (%R10)*

 

Word 5

00000

(0000)

Reserved

The term local PLC is

Word 6

00000

(0000)

Reserved

used here to identify the

Word 7

02002

(07D2)

Retrieve Detailed Channel Status Command number

client PLC—the PLC

Word 8

00005

(0005)

Channel number 5

that initiates the

Word 9

00008

(0008)

Local PLC - Memory type to store Detailed Chan. Stat. (%R)

communications

Word 10

00100

(0064)

Local PLC - Starting address (%R100)

request.

 

 

 

 

*Word 4 (CRS word address) is the only zero-based address in the Command Block. Only this value requires subtracting 1 from the intended address.

(Word 7) Channel Command Number: The command parameter in Word 7 requests that Detailed Channel Status words be returned. If the command is processed successfully, the Detailed Channel Status words will be written to the location specified in Words 9 and 10. Then the CRS word will indicate successful completion of the command. If the specified channel is not currently in use, the latest status will be returned.

GFK-1541B

Chapter 3 Programming Channel Commands

3-29

Page 96
Image 96
GE GFK-1541B manual Retrieve Detailed Channel Status