
84
Teledyne API – Model T400 O
3
Analyzer
083730400A DCN8130
3.4.2
H
ESSEN
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