Teledyne 7120 - NDIR analyzer - Manual (Page 18)

2 Installation Model 7120
2-10
Teledyne Analytical Instruments
When CRC opens again, zero and span are done, and the sample is
being analyzed.
Note: The Remote Probe connector provides signals to operate the
zero and span gas valves synchronously. However, if you
have the –C Internal valve option, which includes zero and
span gas inputs, the 7120 automatically regulates the zero,
span and sample gas flow.
2.3.3.4 Range ID Relays
Four dedicated Range ID relay contacts. For any single application they
are assigned to relays in ascending order. For example: if all ranges have the
same application, then the lowest range is assigned to the Range 1 ID relay,
and the highest range is assigned to the Range 3 ID relay. Range 4 is the Cal
Range ID relay. Figure 2-6 lists the pin connections.
Table 2-6: Remote Calibration Connections
Pin Function
9 + Remote Zero
11 – Remote Zero
10 + Remote Span
12 – Remote Span
40 Cal Contact
41 Cal Contact
Remote Calibration Protocol: To properly time the Digital Remote
Cal Inputs to the Model 7120 Analyzer, the customer's controller must
monitor the Cal Relay Contact.
When the contact is OPEN, the analyzer is analyzing, the Remote Cal
Inputs are being polled, and a zero or span command can be sent.
When the contact is CLOSED, the analyzer is already calibrating. It
will ignore your request to calibrate, and it will not remember that request.
Once a zero or span command is sent, and acknowledged (contact
closes), release it. If the command is continued until after the zero or span is
complete, the calibration will repeat and the Cal Relay Contact (CRC) will
close again.
For example:
1) Test the CRC. When the CRC is open, Send a zero command
until the CRC closes (The CRC will close quickly.)