Strain Guage Indicator: 409-W
REF NO: m59A/om/501
Issue NO: 03
Page 26 of 34
9. Communication Parameter
9.1
Introduction
The unit can be connected in RS-485 communication data link either in multi drop
or repeat mode. Each unit must have unique Serial Number. Entire range of
addresses (1 to 247) may be used. Before starting any communication, choose a
baud rate compatible to the host computer. The serial protocol used is MODBUS
RTU.
Function Code for Modbus
CODE
NAME
Function
01
Read coil status
Use to read Relay and Digital output status
03
Read Holding registers
Use to read PV, Control, RSP output etc.
04
Read input registers
Use to read programmable registers
05
Force single coil
Use to ON /OFF single coil.
16
Preset Multiple register
Use to write programmable register
Table 9.1.
The error checking field contains a 16-bit value implemented as two eight-bit bytes.
The error check value is the result of a Cyclical Redundancy Check (CRC)
calculation performed on the message contents.
9.2
Parameter Address Details
Sr.No
Parameter
Absolute
address
Type
Minimum
value
Maximum
Value
Access
Type
1.
*Relay status1
1
Bit
0
1
R/W
2.
*Relay status2
2
Bit
0
1
R
3.
*Alarm status1
10001
Bit
0
1
R
4.
*Alarm status2
10002
Bit
0
1
R
5.
*Digital Input
10003
Bit
0
1
R
6.
*Alarm 1 Blinking
10004
Bit
0
1
R
7.
*Alarm 2 Blinking
10005
Bit
0
1
R
8.
Process value
30001
Integer
-19999
19999
R
9.
Gross value
30002
Integer
-19999
19999
R
