Prosoft-technology MVI56E-MNETCR Bedienungsanleitung PDF herunterladen (Seite 118)

Reference MVI56E-MNETCR ♦ ControlLogix Platform

User Manual Modbus TCP/IP Multi Client Enhanced Communications Module for Remote Chassis

Page 118 of 159 ProSoft Technology, Inc.

June 14, 2011

5.5 Modbus Protocol Specification

The following pages give additional reference information regarding the Modbus

protocol commands supported by the MVI56E-MNETCR.

5.5.1 Read Coil Status (Function Code 01)

Query

This function allows the user to obtain the ON/OFF status of logic coils used to

control discrete outputs from the addressed Server only. Broadcast mode is not

supported with this function code. In addition to the Server address and function

fields, the message requires that the information field contain the initial coil

address to be read (Starting Address) and the number of locations that will be

interrogated to obtain status data.

The addressing allows up to 2000 coils to be obtained at each request; however,

the specific Server device may have restrictions that lower the maximum

quantity. The coils are numbered from zero; (coil number 1 = zero, coil number 2

= one, coil number 3 = two, and so on).

The following table is a sample read output status request to read coils 0020 to

0056 from Server device number 11.

Adr Func Data Start Pt Hi Data Start Pt Lo Data # Of Pts Ho Data # Of Pts Lo Error Check Field

11 01 00 13 00 25 CRC

1 2 ... 113 114 115 116 117 118 119 120 121 122 123 ... 158 159

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Prosoft-technology MVI56E-MNETCR Bedienungsanleitung Seite 118