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G4 Multi Channel Force Instrument
7-31
The first 32 bytes of data from the instrument to the fieldbus are mandatory.
Bytes 0 and 1:
Contains the actual instrument error information (the value 0 means no error). See
‘7. Communication – Modbus protocol – Instrument error’.
Bytes 2 and 3:
The actual status information for the instrument, see ‘7. Communication –
Modbus protocol – Instrument status’.
Byte 4:
The ‘Command acknowledge’. It will be equal to the command number if the command
was successfully executed. If the command failed byte 4 will have the value 240
(hex F0).
Byte 5:
The possible ‘Command error’ code. The error code is explained in chapter
‘9. Troubleshooting – Error codes’. This byte will be zero if a command is correctly
executed.
Bytes 6 and 7:
These two bytes is the starting address of the reading area following in bytes 8 to 31.
The address defines the first of the 12 consecutive modbus registers in the read area.
See chapter ‘7. Communication – Modbus protocol’ for details on modbus register
address definitions.
Bytes 8 to 31:
These 24 bytes is the area used when the user wants to read any data that is
accessible through modbus registers. The address (number) of the first register is
defined in bytes 6 and 7 and the instrument will keep the 24 bytes (12 registers)
updated.