Owner's Manual

GDX-350 Sensor Transmitter
P/N: 5600-9001 Rev 2 45
5.15. Modbus Register and Function Code Summary
The following tables identify GDX-350 Modbus register locations and function codes. “Chan 1”
designations represent the EC channel while “Chan 2” represents the LEL/4-20 mA Input channel.
Read Only Discretes
VARIABLE ALIAS READ FUNCTION CODE WRITE FUNCTION CODE
Chan 1 Alarm 1 2001 2 NA
Chan 1 Alarm 2 2002 2 NA
Chan 1 Fault 2003 2 NA
Chan 2 Alarm 1 2004 2 NA
Chan 2 Alarm 2 2005 2 NA
Chan 2 Fault 2006 2 NA
K1 2007 2 NA
K2 2008 2 NA
K3 2009 2 NA
Chan 1 Cal Mode 2010 2 NA
Chan 2 Cal Mode 2011 2 NA
Read/Write Coils
VARIABLE ALIAS READ FUNCTION CODE WRITE FUNCTION CODE
Alarm Ack/Reset 12001 1 5
Note: After writing a TRUE to this register, it resets back to FALSE automatically.
Read Only Registers
VARIABLE ALIAS READ FUNCTION CODE WRITE FUNCTION CODE
D2A Raw Chan 1
1
31001 4 NA
D2A Raw Chan 2
1
31002 4 NA
A2D Raw Chan 1
2
31003 4 NA
A2D Raw Chan 2
2
31004 4 NA
Chan 1 Status
3
31005 4 NA
Chan 2 Status
3
31006 4 NA
Alarm Status Word
4
31007 4 NA
Transmitter Status Word
5
31008 4 NA
Chan 1 Sensor Life
6
31009 4 NA
Chan 2 Sensor Life
6
31010 4 NA
Chan 1 Sensor Temperature
7
31011 4 NA
Chan 2 Sensor Temperature
7
31012 4 NA
1 Calibrated 10-bit value representing the D2A value of 0 to 1023 for -25 to 105 %FS (200=0% and 1000=100%).
IMPORTANT: Read registers 31001/31002 to create readings that match GDX-350 display values! These
should also be read by GDX-1600 Modbus masters.
2 10-bit value representing the A2D value of 0 to 1023 before calibration constants are applied.