Agilent Technologies TwisTorr 74FS AG Rack Mode D'emploi page 278

17 Technical Information
Profibus Option

As a general rule, unrecoverable communication errors make
each machine to jump to the state immediately following the
power-on state (WAIT_PRM or SRC_ADDR).
Message Mapping
The communication is based on the continuous data exchange
capability of the ProfiBus standard, where the master sends
continuously the entire slave configuration and reads back the
entire slave status.
For this purpose one Input (from slave to master) and one
Output (from master to slave) buffers are provided. All the
needed parameters are mapped inside each buffer.
The following tables summarise the ProfiBus parameter access,
related to the corresponding windows serial protocol (for this
protocol please refers to the serial interface paragraph).
The interface doesn't any scaling operation on the read/written
parameters. It acts only as a gateway between the ProfiBus
network and the pump's controller serial interface. As a
consequence of this, the scale and the meaning of some
parameters depends directly to the specific model of Turbo
Pump controller connected to the interface.
278/300
Internal serial link Data Exchange is suspended (only for
output data) if the ProfiBus State machine is not in Data
Exchange mode
TwisTorr 74 FS AG Rack Controller User Manual / 87-901-055-01