FANUC Robotics America GFK-1541B User Manual

Page 130

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GFK-1541B

Chapter 4 Programming Modbus/TCP Channel Commands

4-15

4

Command 3003, Example 3 – Read Exception Status

Read the Exception Status from the remote Modbus/TCP server. Store the ExceptionData at
location %Q4(bit mode). Return the COMMREQ Status word to %R10.

Dec (Hex)

Word 1

00008 (0008)

Length of Channel command Data Block

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

Word 6

00000 (0000)

Reserved

Word 7

03003 (0BBB)

Read from a Modbus/TCP Device

Word 8

00006 (0006)

Channel number (6)

Word 9

00007 (0007)

Modbus Function Code

Word 10

00072 (0048)

Local PLC Memory Type

Word 11

00004 (0004)

Local PLC Starting Address

Word 12

00000 (0000)

Reserved

Word 13

00001 (0001)

Data Size

Word 14

00001 (0001)

Unit Identifier

* 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:

Word 7 identifies the COMMREQ as a Read Exception

Status from the Modbus/TCP device.

(Word 8) Channel Number:

Word 8 identifies the channel number previously allocated for

communication with the remote Modbus/TCP server.

(Word 9) Modbus Function Code:

Word 9 specifies Modbus Function Code 7, Read Exception

Status.

(Word 10) Local PLC Memory Type:

Words 10-11 specify the location in the local PLC where

the Ethernet Interface will store data received from the remote device . Valid values for Word 10
are listed on page 4-14.

(Word 11) Local PLC Memory Address:

Word 11 determines the starting address in the local

PLC in which the data from the remote device is to be stored. The value entered is the offset (1-
based) from the beginning of PLC memory for the memory type and mode specified in Word 10.
This offset will be either in bits, bytes, or words depending on the mode specified. Valid ranges
of values depend on the PLC’s memory ranges. The user is responsible for assuring that this area
is large enough to contain the requested data without overwriting other application data.

(Word 12) Reserved:

Word 12 is reserved and must be set to zero.

(Word 13) Data Size:

Word 13 is the data sizeand must be set to 1.

(Word 14) Unit Identifier:

Default is 1. This field is typically used by Ethernet to Serial bridges to

specify the address of a Modbus Slave on a multidrop link. The Modbus/TCP Unit Identifier is a
special control code used in a Modbus/TCP message block. This value is 1 for most Modbus/TCP
messages.

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