Rockwell Automation 1785-ENET PLC-5 Ethernet Interface Module Installation Instructions User Manual

Page 28

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28 PLC-5 Ethernet Interface Module

Publication 1785-IN019B-EN-P - January 2007

The MSG instruction transfers data in packets. Each packet can contain up to 709 words for
Ethernet controllers and interface modules. If your message transfer contains more words
than fit in one packet, the transfer requires more than one packet of transfer data. The more
packets of data to transfer, the longer the total transfer takes.

Enter Parameters

The control block is where all of the information relating to the message is stored. Ethernet
message instructions use two consecutive control blocks:

Use your programming software package to enter the control block address. After entering
the control block, the programming terminal automatically displays a data entry dialog, from
which you enter instruction parameters that are stored at the control block address.

Parameter Descriptions

When you enter 3A as the port number, an Ethernet instruction entry dialog appears. In
addition to the information you entered previously, this dialog includes a field for entering the
Host/Internet (IP) address. Enter the IP address of the destination controller here.

This Block

Contains

First

Message information

Second

Destination address

IMPORTANT

Because Ethernet messages need two consecutive control blocks, the
message control block that you specify must start on an even element
number.

This Parameter

Specifies

Command Type

Whether the MSG instruction performs a read or write operation. The software toggles
between: PLC-5 Typed Read, PLC-5 Typed Write, PLC-5 Typed Write to SLC, PLC-5 Typed
Read from SLC, SLC Typed Logical Read, SLC Typed Logical Write, PLC-2 Unprotected
Read, PLC-2 Unprotected Write, PLC-3 Word Range Read, and PLC-3 Word Range Write.

PLC-5 Data Table
Address

The data file address of the controller containing the message instruction. If the MSG
operation is write, this address is the starting word of the source file. If the MSG
operation is read, this address is the starting word of the destination file.

Size in Elements

The number of elements (1...1000) to be transferred.

Destination Address The starting address of the source or destination file in the target controller.

Port Number

The channel for message communications. Communications through the Ethernet
interface module use channel 3A.

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