Teledyne Analytical Instruments
Thermal Conductivity Analyzer
Installation 3
3-11
•
The range in use (00 = Range 1, 01 = Range 2, 10 = Range 3,
11 = Range 4)
•
The span of the range (0-100 %, etc)
•
Which alarms—if any—are disabled (AL–x DISABLED)
•
Which alarms—if any—are tripped (AL–x ON).
Each status output is followed by a carriage return and line feed.
Input: The input functions using RS-232 that have been imple-
mented to date are described in Table 3-7.
Table 3-7: Commands via RS-232 Input
Command
Description
as<enter>
Immediately starts an autospan.
az<enter>
Immediately starts an autozero.
rp<enter>
Allows reprogramming of two
System
functions:
APPLICATION
(gas use) and
ALGORITHM
(linearization).
st<enter>
Toggling input. Stops/Starts any status message output
from the RS-232, until st<enter> is sent again.
Implementation: The RS-232 protocol allows some flexibility in its
implementation. Table 3-8 lists certain RS-232 values that are required by
the Model 2000A implementation.
Table 3-8: Required RS-232 Options
Parameter
Setting
Baud
2400
Byte
8 bits
Parity
none
Stop Bits
1
Message Interval
2 seconds
3.4
Gas Connections
The gas fittings are accessed through holes on the underside of the
analyzer chassis, as shown in Figure 3-8. Use
1
/
8
NPT threaded conversion
fittings to convert pipe to tube for these connectors.
There are no gas control valves inside the main chassis. A sample
system must be provided for introduction of zero and span gas, as well as
sample gas, into the sample path, and for controlling the flowrates through
the sample and reference paths of the analyzer.