Allen-Bradley MicroLogix 1400 User Manual

Publication 1766-RM001A-EN-P - October 2008
Protocol Configuration 619
Modbus Commands
The controller configured for Modbus RTU Slave responds to the Modbus
command function codes listed in below:
40257…40512 Read/Write Modbus Holding Register space (2nd Holding Register file). 3, 6, 16
40513…40768 Read/Write Modbus Holding Register space (3rd Holding Register file). 3, 6, 16
40769…41024 Read/Write Modbus Holding Register space (4th Holding Register file). 3, 6, 16
41025…41280 Read/Write Modbus Holding Register space (5th Holding Register file). 3, 6, 16
41501…41566 Read/Write System Status File 3, 6, 16
41793…42048 Read/Write Modbus Holding Register space (6th Holding Register file). 3, 6, 16
Modbus Slave to MicroLogix Memory Map - Detail
Modbus Addressing Modbus Address Reference Modbus Function Code (decimal)
Supported Modbus Commands as a Modbus RTU Slave
Command Function Code
(decimal)
Subfunction Code
(decimal)
Read Coil Status 1 -
Read Input Status 2 -
Read Holding Registers 3 -
Read Input Registers 4 -
Write Single Coil
(1)
(1) Broadcast is supported for this command.
5-
Write Single Holding Register
(1)
6-
Echo Command Data 8 0
Clear Diagnostic Counters 8 10
Write Multiple Coils
(1)
15 -
Write Multiple Holding Registers
(1)
16 -
Supported Modbus Commands as a Modbus RTU Master
Command Function Code
(decimal)
Subfunction Code
(decimal)
Read Coil Status 1 -
Read Input Status 2 -
Read Holding Registers 3 -
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Allen-Bradley MicroLogix 1400 Specifications

General

Processor	32-bit
Expansion Modules	Up to 7 expansion I/O modules
Power Supply	24V DC or 120/240V AC
Programming Software	RSLogix 500
Communication Ports	Ethernet, RS-232/RS-485 combo port
Controller Type	Programmable Logic Controller (PLC)
Series	MicroLogix
Digital Outputs	12
Analog Inputs	6 (embedded)
Analog Outputs	2 (embedded)
High-Speed Counter	6 high-speed counters
Pulse Output	2 (embedded)
Ethernet Port	Yes