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Teledyne API T803 CO2/O2 Analyzer Operation Manual Communications Setup and Operation
119
host computer and only when they receive a command containing their own
unique ID number.
The Hessen protocol is designed to accomplish two things: to obtain the status of
remote instruments, including the concentrations of all the gases measured; and to
place remote instruments into zero or span calibration or measure mode. API’s
implementation supports both of these principal features.
The Hessen protocol is not well defined, therefore while API’s application is
completely compatible with the protocol itself, it may be different from
implementations by other companies.
Note
The following sections describe the basics for setting up your instrument to
operate over a Hessen Protocol network. For more detailed information as
well as a list of host computer commands and examples of command and
response message syntax, download the Manual Addendum for Hessen
Protocol from the Teledyne API web site: http://www.teledyne-
api.com/manuals/.
6.5.2.1. HESSEN COM PORT CONFIGURATION
Hessen protocol requires the communication parameters of the T803’s COM
ports to be set differently than the standard configuration as shown in the table
below.
Table 6-4: RS-232 Communication Parameters for Hessen Protocol
PARAMETER STANDARD HESSEN
Baud Rate 300 – 115200 1200
Data Bits 8 7
Stop Bits 1 2
Parity
None Even
Duplex Full Half
To change the baud rate of the T803’s COM ports, See Section 6.2.2.
To change the rest of the COM port parameters listed in the table above, see
Section 6.2 and Table 6-1.
Note
Make sure that the communication parameters of the host computer are also
properly set.
In addition, rather than issuing commands to the instrument in rapid
succession, bear in mind that the instrument software has a 200 ms latency
period before it responds to commands issued by the host computer.
6.5.2.2. ACTIVATING HESSEN PROTOCOL
Once the COM port has been properly configured, the next step in configuring
the T803 to operate over a Hessen protocol network is to activate the Hessen
mode for COM ports and configure the communication parameters for the port(s)
appropriately.
07276B DCN6418