Campbell Scientific CR510 Basic Datalogger - Manual (Page 195)

APPENDIX F. MODBUS ON THE CR10(X) AND CR510
F-3
The register data is returned as two bytes per
register and two registers per input location.
Response for example 2:
Hex
Slave address 11
Function 03
Byte Count 08
Data Hi (Register 40009) C0
Data Lo (Register 40009) 00
Data Hi (Register 40010) 44
Data Lo (Register 40010) 0A
Data Hi (Register 40011) 00
Data Lo (Register 40011) 00
Data Hi (Register 40012) 1F
Data Lo (Register 40012) 00
Error check (LRC or CRC) --
The contents of 40008 and 40009 are C0 00 44
0A hex or a value of 555.000 in input location 5.
Input location 6 = 0.
For complete documentation please refer to the
Modicon publication referenced above.