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G4 Multi Channel Force Instrument
7-29
Data from the fieldbus (Outputs in the master)
General
This 16 bytes block is mandatory, i.e. it is always mapped to the fieldbus in the
instrument.
Byte Contents
00 Command
01 Number of registers to write
02 Start address, Read/Write
MSB
03 Start address, Read/Write
04 Write register 1
MSB
05 Write register 1
06 Write register 2
MSB
07 Write register 2
08 Write register 3
MSB
09 Write register 3
10 Write register 4
MSB
11 Write register 4
12 Write register 5
MSB
13 Write register 5
14 Write register 6
MSB
15 Write register 6
Byte 0:
The command byte is used when setting the read window starting address, writing data
to the instrument and to issue various commands.
Commands:
0 No action
250 (hex FA) Change read window
251 (hex FB) Write data
252 (hex FC) Clear the Program reset bit in the Instrument Status register.
Plus commands according to the manual, chapter ‘7. Communication –
Modbus protocol – Command register’.
Note that a new command is detected when the content of the command register is
changed. If the same command is used more than once another command e.g. 0 must
be used in between.
The response to a given command is the ‘Command acknowledge’ and the
‘Command error’ bytes that are described below in section ‘Data to the fieldbus’.
Byte 1:
Used to define the number of registers to write.