FISCHER DE43, Operating Manual, Page: 17 / 28

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BA_EN_DE43 17 / 28
4.3.4 Function code 0x03: Read Holding Registers
This Function Code is used to read the Holding Register. The maximum pos-
sible number of registers that can be addressed in one message is 125.
Request The request contains the address of the first register that is to be read and the
number of registers that need to be read. The addressing of the register starts
with 0; the numbering of the registers starts with 1.
0x03 MSB LSB MSB LSB
5 1 2 3 4 Byte
Byte Field name Size Value range
1 Function Code 1 byte 0x03
2.3 Start Address 2 bytes 0x0000 to 0xFFFF
4.5 Number of registers 2 bytes 0x0001 to 0x007D (1…125)
The DE43 Transmitter has precisely 1 Holding Register with the address
0x0000.
Bit Data type Description State
0 Unsigned Integer Pressure sensor
1 Sensor error 0 or 1
1 Unsigned Integer Pressure sensor
1 Pressure too low 0 or 1
2 Unsigned Integer Pressure sensor
1 Pressure too high 0 or 1
3 Unsigned Integer RESERVED 0 or 1
4 Unsigned Integer Pressure sensor
2 Sensor error 0 or 1
5 Unsigned Integer Pressure sensor
2 Pressure too low 0 or 1
6 Unsigned Integer Pressure sensor
2 Pressure too high 0 or 1
7 Unsigned Integer RESERVED 0 or 1
8 Unsigned Integer Temp. sensor Sensor error 0 or 1
9 Unsigned Integer Temp. sensor Temperature too low 0 or 1
10 Unsigned Integer Temp. sensor Temperature too high 0 or 1
11 Unsigned Integer RESERVED 0 or 1
12 Unsigned Integer General System error 0 or 1
13 Unsigned Integer RESERVED 0 or 1
14 Unsigned Integer RESERVED 0 or 1
15 Unsigned Integer RESERVED 0 or 1
Response The response contains two bytes for each read register; therefore the number of
bytes is twice of the number of registers (N).
0x03 2N MSB
1 2 3 Byte
...
4
LSB MSB LSB
Register 1 Register N
Byte Field name Size Value range
1 Function Code 1 byte 0x03
2 Number of bytes 2 bytes 2N
3.4 Holding Register N x 2 Byte 16 Bit value