Rosemount 2700 - Integer Measurements

A-38
MODEL 2700 APPENDIX A
MODBUS PROTOCOL
Dual measurement
Register = 17
- Measurement values are in Integer format, unsigned.
- Negative values are in two’s complement.
- Measurements on the Solu Cube display are truncated to form measurements in Integer format.
measurement value = Integer x Resolution
See Modbus Tables for Resolution.
Example: Read Primary measurement of Sensor1 - conductivity
Sensor_number = 1
Register = 1
Function Code 04 Read Input Registers
Starting Address 01
Number of Points 01
Register contents in hexadecimal
30001: 01F6H
Integer = 01F6H
= 502
To find Measurement type, read Units and Sensor Type.
Sensor_number = 1
Register = 33
Function Code 04 Read Input Registers
Starting Address 33
Number of Points 01
Register contents in hexadecimal
30033: 0200H
Unit_Value = quotient(0200H/100H)
= 2
Sensor_Type_Value = remainder(0200H/100H)
= 0
From Modbus Tables,
Units µS/cm
Sensor Type .01/cm
Resolution = .01uS/cm
measurement value = Integer x Resolution
= 502 x .01uS/cm
= 5.02 uS/cm
Conductivity 5.02 µS/cm
Sensors Active 18
Number of active sensors.
Appendix
References
1. Modicon Modbus Protocol Reference Guide, PI-MBUS-300 Rev. G, November 1994; MODICON, Inc., Industrial
Automation Systems, North Andover MA
2. Modicon Modsoft Lite Programmer User Manual, GM-MSLT-001 Rev. B, July 1994; MODICON, Inc., Industrial
Automation Systems, North Andover MA