Evolution Controls EVO/ECM-Modbus - Register 19 - Motor 1 Low RPM Limit; Register 20 - Motor 2 Low RPM Limit; Register 21

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©Evolution

Controls Inc.

10-Sept-2020

EVO/™ECM-Modbus RTU Series 2 Page 19

Application Guide

Evolution Controls Inc.

San Diego, CA USA

EVO/ECM-MODBUS RTU PROTOCOL

Read Registers Command (03)

Address

Command

Code

Starting Register

Number of Registers

Error Check

1-247

1-26

CRC-16

• Unit, group 1, or group 2 address must be 1-247 (one byte)

• The command code is 03 (one byte).

• The starting register is two bytes long. The value must be 00 00 when addressing an EVO/ECM-

Modbus RTU.

• The number of registers is two bytes in length. The high byte is always 00. The low byte is an

integer between 1 and 26.

Reply to Modbus Master

Byte

Data

Address

Command

Code

Count

Error Check

1-247

2-52

CRC-16

• The byte count is 2 times the number of registers requested in the query. The EVO/ECM-

Modbus RTU allows polling of up to 26 registers, so this number will be an even number

between 2 and 52.

• Register 1 is always the first register in the data string.

Evolution Controls EVO/ECM-Modbus - Register 19 - Motor 1 Low RPM Limit; Register 20 - Motor 2 Low RPM Limit; Register 21 - Motor 3 Low RPM Limit