Teledyne 6200E - Sulfides Analyzer - Manual (Page 149)

Model 6200E Instruction Manual Operating Instructions
M6200E Rev: A1 149
6.12.4. Using the M6200E with a Hessen Protocol Network
6.12.4.1. General Overview of Hessen Protocol
The Hessen protocol is a multidrop protocol, in which several remote instruments are connected via
a common communications channel to a host computer. The remote instruments are regarded as
slaves of the host computer. The remote instruments are unaware that they are connected to a
multidrop bus and never initiate Hessen protocol messages. They 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 Analytical Instruments’ web site:
http://www.teledyne-ai.com/manuals.
6.12.4.2. Hessen COMM Port Configuration
Hessen protocol requires the communication parameters of the M6200E’s COMM ports to be set
differently than the standard configuration as shown in the table below.
Table 6-27: RS-232 Communication Parameters for Hessen Protocol
Parameter Standard Hessen
Data Bits 8 7
Stop Bits 1 2
Parity None Even
Duplex Full Half
To change the rest of the COMM port parameters and modes. see Section 6.10.8.
To change the baud rate of the M6200E’s COMM ports, see Section 6.10.9.
NOTE
Make sure that the communication parameters of the host computer are also properly
set.
Also, the instrument software has a 200 ms. latency before it responds to commands
issued by the host computer. This latency should present no problems, but you should be
aware of it and not issue commands to the instrument too frequently.