YSI IQ SensorNet MIQ/A-MOD Module - Manual (Page 26)

Data transmission MIQ/(A-)MOD
26 ba76021e01 01/2012
Determining the number
of registers to be read
The number of registers to be read is maximum 240.
Example: Read all data of X sensors
Example of a
Modbus query
and Modbus response
Query of all sensor information of the sensor with the sensor number
S02:
Number of sensors
(X) Number of registers
1 8
2 16
3 24
... ...
30 240
Modbus query
Byte Value Information Meaning of the value
1 01h Modbus address of
the MIQ/MC-MOD 01h --> 1
2 04h Function 04h --> 4
Read Input Register
(see section 4.3)
3 00h Start address HI 0008h --> 8
Start with register 9
(Modbus counting method)
4 08h Start address LO
5 00h Number of HI registers 0008h --> 8
8 registers
6 08h Number of LO
registers
7 70h CRC (HI) Checksum (CRC)
8 0Eh CRC (LO)