083730300A DCN8101 Communications and Remote Operation 87
3.4.2 HESSEN
Hessen is a multidrop protocol, in which several remote instruments (slaves) are
connected via a common communications channel to a host computer. Slaves respond
only to commands sent by the host using their unique identification.
Important
Create a unique identification number for each
instrument in the multidrop chain via the
Setup>Vars>Instrument ID menu.
The Hessen protocol is not strictly defined; therefore, while Teledyne API’s application
is completely compatible with the protocol itself, it may be different from
implementations by other companies.
3.4.2.1 HESSEN COM PORT CONFIGURATION
ConFigure the COM1/COM2 port for Hessen protocol through the
Setup>Comm>COM1[COM2] menu: select COM1[COM2] Protocol and press Edit to
select HESSEN, then press Accept.
Ensure that the communication parameters of the host computer are also properly set.
Figure 3-3. Serial Communication, Setting Hessen Protocol
Note
The instrument software has a 200 ms
latency period
before it responds to commands issued by the host
computer.
This latency should present no problems, but
be mindful of issuing
commands to the instrument too
frequently.