FANUC Robotics America GFK-1541B User Manual

Page 70

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GFK-1541B

Chapter 3 Programming Channel Commands

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COMMREQ Function Block

The COMMREQ Function Block is the ladder instruction that triggers the execution of the
Channel command. In the COMMREQ Function Block, you specify the rack and slot location of
the Ethernet Interface, a task value, and the address of a location in memory that contains the
Command Block. There is also a fault output on the COMMREQ Function Block that indicates
certain programming errors.

COMMREQ Command Block

The COMMREQ Command Block is a structure that contains information about the Channel
command to be executed. The Command Block consists of two parts:

Common Area - includes the address of the COMMREQ Status word (CRS word).

Data Block Area - describes the Channel command to be executed.

When the COMMREQ function is initiated, the Command Block is transferred to the Ethernet
Interface for action.

SRTP Channel Commands

The Channel commands are a set of client PLC commands used to communicate with a server
PLC.

Advantages of Channel Commands

The advantage of Channel commands is their ability to establish a channel to execute multiple
periodic

reads or writes with a single initiation of a COMMREQ function. A Channel command

can also be used to execute a single read or write.

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Up to 32 channels (numbered 1–32) can be established by a Series 90-70 Ethernet Interface.

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Up to 16 channels (numbered 1–16) can be established by a Series 90-30 Ethernet Interface.
(If the Series 90-30 Ethernet Interface supports Modbus/TCP Channels, the 16 available
channels are shared between SRTP and Modbus/TCP.)

The channel number is specified in the Command Block for the Channel command. The channel
can be monitored using the Channel Status bits and the Detailed Channel Status words.

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