Teledyne 9110TH - Nitrogen Oxides Analyzer - Manual (Page 179)

Operating Instructions Model 9110TH NOx Analyzer
Teledyne Analytical Instruments 159
only respond to commands from the 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.
The following subsections 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/index.asp .
4.15.4.2. Hessen Com Port Configuration
Hessen protocol requires the communication parameters of the 9110TH/M’s com ports
to be set differently than the standard configuration as shown in the table below.
Table 4-34: RS-232 Communication Parameters for Hessen Protocol
Parameter Standard Hessen
Data Bits 8 7
Stop Bits 1 2
Parity None Even
Duplex Full Half
Note Ensure that the communication parameters of the host computer are
properly set
Be aware that the instrument software has a 200 ms latency response to
commands issued by the host computer.
Operation via modem is not available over any com port on which
HESSEN protocol is active.