Teledyne 4020 - Hydrocarbon analyzer - Manual (Page 38)

Installation Model 4020
Teledyne Analytical Instruments 22
0–1 volt across the terminals allows Span mode to
terminate when done. A synchronous signal must
open and close external span valve appropriately.
Cal Contact: This relay contact is closed while analyzer is spanning
and/or zeroing. (See Remote Calibration Protocol below.)
Table 3-5: 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 4020 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 quickly close.)
2. When the CRC closes, remove the zero command.
3. When CRC opens again, send a span command until the
CRC closes. (The CRC will quickly close.)
4. When the CRC closes, remove the span command.