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D-1

Scanner

2000 microEFM Appendix D

Appendix D—Modbus

Communications Protocol

Firmware Version: 4.10

Introduction

The communications protocol for the Scanner 2000 is in accordance with Modicon, Inc. RTU Mode

Modbus® as described in ModiconModbusProtocolReferenceGuide, PI-MBUS-300 Rev. J, June 1996. All

registers are implemented as 4X or holding registers. Reading of registers is implemented via function code

03H (Read Holding Registers). Writing to registers is implemented via function code 10H (Preset Multiple

Registers). The instrument provides Enron Modbus® compliant downloads for interval, daily and event

records. For details on Enron Modbus®, refer to SpecicationsandRequirementsforanElectronicFlow

MeasurementRemoteTerminalUnitforEnronCorp., Dec. 5, 1994.

Supported Commands

The Modbus® functions supported by the Scanner 2000 are as follows:

Function Code (Hex) Description

03 Read Holding Registers

05 Preset Boolean

(for Enron event record acknowledgement)

10 Preset Multiple Registers

11 Report Slave ID

For the read holding and preset multiple registers, the instrument supports the full 250 bytes of data in a

message. This corresponds to 125 registers in 16-bit holding register size and 62 registers in 32-bit holding

The report slave ID function code returns the following registers:

• Product Code

• Register Table Number

• Firmware Version

• Manufacture Date

• Sales Date

• Serial Number 1

• Serial Number 2

• Power Mode

• Connected Port (0 = connected to Port 1; 1 = connected to Port 2)

• Port Mode

• Port SlaveAddress

• Port BaudRate

Cameron Scanner 2000 microEFM User Manual

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