4

TASK: This must always be set to zero for the Ethernet Interface

Caution

Entering a number other than zero for TASK may cause the EthernetInterface to fail.

OKOutput: The OK output is set if the PLC CPU was successful in handing off the

COMMREQ to the Ethernet Interface.

FT Output: The FT output is set if the PLC (rather than the Ethernet Interface) detects that the COMMREQ fails. In this case, the other status indicators are not updated for this COMMREQ. See Section 3 for more information.

The COMMREQ Command Block

When the COMMREQ function is initiated, the Command Block is sent from the PLC

CPU to the Ethernet Interface. The Command Block contains the details of a Channel

Command to be performed by the Interface.

The address in CPU memory of the Command Block is specified by the IN input of the COMMREQ Function Block. This address may be in any word-oriented area of memory (%R, %AI, or %AQ). The Command Block is set up using an appropriate programming instruction (the BLOCK MOVE Function Block is recommended).

The Command Block has the following structure:

Word 1

Data Block Length (words)

Word 2

WAIT/NOWAIT Flag = 0

Word 3

CRS Word Pointer Memory Type

Word 4

CRS Word Pointer Offset

Word 5

Reserved

Word 6

Reserved

Words 7 up to 31

Data Block (Channel Command Details)

(decimal)

 

When entering information for the Command Block, refer to these definitions:

(Word 1) Data Block Length: This is the length in words of the Data Block portion of the Command Block (up to 25 words-decimal). The Data Block portion starts at Word 7 of the Command Block. The length is measured from the beginning of the Data Block at Word 7, not from the beginning of the Command Block. The correct value for each com- mand, and the associated length of each command, is specified in Section 3.

(Word 2) WAIT/NOWAIT Flag: This flag must be set to zero for TCP/IP Ethernet Commu- nications.

GFK-1004B

Chapter 4 Programming Communications Requests

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GE GFK-1004B user manual Commreq Command Block