Franklin Electric SUBMONITOR CONNECT MT1111, Installation And Operation Manual

Page: 37 / 232

COMMUNICATIONS
Modbus RTU Communication
37
Modbus RTU Communication
The SubMonitor Connect can be controlled and monitored through the Modbus RTU protocol over an RS-
485 connection. Modbus follows a simple client-server model. Server devices perform data read/write
requests which are issued from a client device such as a Programmable Logic Controller (PLC) or Building
Management System (BMS). Assignable addresses for server devices range from an address of 1 to a
theoretical maximum of 247.
As a server device, the SubMonitor Connect communicates all data using only 16-bit holding registers.
Addressing for the registers is partitioned into blocks that are multiples of 100 to group functionally similar
data. If the monitor is configured to accept commands via remote communications, it can be commanded to
start, stop, and reset faults.
Modbus addresses can be found in the parameter tables throughout this publication.
The Modbus connector provides RS-485 connection for Modbus Remote Terminal Unit (RTU)
communication. This interface is capable of supporting 128 total devices at a maximum baud rate of 115200,
at a maximum distance of 2000 feet. Refer to the table below for maximum baud rates and their respective
maximum distances.
Maximum Distance Maximum Baud Rate
2000 ft. 115200
3000 ft. 76800
4000 ft. 19200