Table 7: Function Code 03 Read Holding Registers - Sensor Electronics SEC Millenium Series Instruction And Operation Manual

Query Exception Status Message
Field Name Example (Hex)
Slave Address
Function Code
CRC Low Byte
CRC High Byte
Function Code 03 - Read Holding Registers
The following holding registers (4X references) are supported by the SEC 3120
for one or multiple sequential function code 03 read 16-bit binary operations (multiple
read operations must be sequential starting at the specified valid holding register address
in the read list). Broadcast mode is not supported for this function.

Table 7: Function Code 03 Read Holding Registers

Internal Holding
Register Register
Address Address
x = sensor number (1 - 8)
2x00 42x01
2x01 42x02
2x02 42x03
2x03 42x04
2x04 42x05
2x05 42x06
2x06 42x07
2x07 42x08
2x08 42x09
*These registers are scaled by Sensor Gas Factor (2x08). To obtain the real floating point
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
11
07
4C
22
Function Code 03- Read Sensor Register Description
(Data bits and Parameter Specifics)
*Scaled Sensor Gas Concentration
Bit-mapped Sensor Operating Status:
Bit 0,1: alarm status (0,0 = no alarm, 0,1 = low
alarm, 1,0 = mid alarm, 1,1 = high alarm.
Bit 2: fault alarm status (1 = fault, 0 = no)
Bit 3: self test (1 = testing, 0 = not)
Bit 4: cell test warning (1 = have warning, 0 = no)
Bit 5: init/warm (1 = init/startup, 0 = idle/run)
Bit 6: sensor missing (1 = missing, 0 = ok)
Bit 7: calibration (1 = calibrating, 0 = not)
Bit 8 - 15: **Sensor Status Code (8 bit integer)
Sensor Firmware Version (1 – 255)
*Scaled Low Sensor Alarm Set Point
*Scaled Mid Sensor Alarm Set Point
*Scaled High Sensor Alarm Set Point
*Scaled Sensor Calibration Value
*Scaled Sensor Range Value
Sensor Gas Factor
Page 26 Of 46
December 2012
Response Exception 1
Field Name Example (Hex)
Slave Address
Function Code
Exception Code
CRC Low Byte
CRC High Byte
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228
11
87
01
83
F5