Rockwell Automation 1405-M620 Operating Instructions - Manual (Page 11)

Publication 1405-IN002C-EN-P - November 2004
Bulletin 1405 (M620) Operating Instructions 11
Modbus Communications The M620 is available with an RS-485 half-duplex communications
port which supports Modbus RTU slave protocol version 1.0. The
following Modbus commands are supported:
03 (0x03) Read Holding Registers
16 (0x10) Write Multiple Registers
43 (0x2B) Read Device Identification
The port may be configured during instrument setup. The baud rate
may be set to 9.6 K or 19.2 K bits per second. The Modbus address
may be set in the range 1 to 257.
The M620 equipped with Modbus includes 2 LEDs which display
Modbus status and Network status.
Modbus Port Connections
Connections to the Modbus port are made via a 3-pin connector as
shown below:
1
2
3
Rx Tx-
Grd
Rx Tx+
Terminating resistors are not included in the M620. If
needed, terminating resistors must be provided and
installed by the user.
Modbus Memory Map
The tables below provide a cross-reference of Modbus register
address to metered value along with data type.
IMPORTANT