Manual

4.0 The Modbus RS-485 Output & Commands Implemented

The default communication parameters are 8 bits, no parity and 1 stop bit. Please note that

all Modbus communication is via RS-485. The instruments can support a two wire

multidrop network of 255 units. If the connection is to the master on USB, an RS-485 to

USB converter is required.

4.1 Coils

These single-bit values are readable and changeable from the master. The data will be returned

with the lowest addressed coil in the LSB of the data. Unused bits in the data will be set to 0. True

is a 1 and False is 0.

4.1.1 Valid Command(s)

Code Name Broadcast

0x01 Read Coil Status No

0X05 Force Single Coil Yes

4.1.2 Format

16-bit word format

MSB LSB

Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

4.1.3 Valid Addresses

00001 – 00XXX

4.1.4 Definitions

Address Function Default

00001 Access code enabled False

00002 RS-485 enabled True

00003 4-20 mA enabled False

CL500 Modbus (3/09)

Rev. 1.3