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Optional Hardware and Software Model GFC7001E Carbon Dioxide Analyzer
Teledyne Analytical Instruments 80
5.10. CONCENTRATION ALARM RELAY (OPTION 61)
The Teledyne “E” series analyzers have an option for four (4) “dry contact” relays on the rear panel of the
instrument. This relay option is different from and in addition to the “Contact Closures” that come standard
on all TAI instruments. The relays have 3 pins that have connections on the rear panel (see Figure 5-19).
They are a Common (C), a Normally Open (NO), & a Normally Closed (NC) pin.
Figure 5-19: Concentration Alarm Relay
Alarm 1 “System OK 2”
Alarm 2 “Conc 1”
Alarm 3 “Conc 2”
Alarm 4 “Range Bit”
“Alarm 1” Relay
Alarm 1 which is “System OK 2” (system OK 1, is the status bit) is in the energized state when the
instrument is “OK” & there are no warnings. If there is a warning active or if the instrument is put into the “DIAG”
mode, Alarm 1 will change states. This alarm has “reverse logic” meaning that if you put a meter across the
Common & Normally Closed pins on the connector you will find that it is OPEN when the instrument is OK. This
is so that if the instrument should turn off or loose power, it will change states & you can record this with a data
logger or other recording device.
“Alarm 2” Relay & “Alarm 3” Relay
The “Alarm 2 Relay” on the rear panel, is associated with the “Concentration Alarm 1” set point in the
software & the “Alarm 3 Relay” on the rear panel is associated with the “Concentration Alarm 2” set point in the
software.
Alarm 2 Relay CO Alarm 1 = xxx PPM
Alarm 3 Relay CO
2
Alarm 2 = xxx PPM
Alarm 2 Relay CO Alarm 1 = xxx PPM
Alarm 3 Relay CO
2
Alarm 2 = xxx PPM
The Alarm 2 Relay will be turned on any time the concentration set-point is exceeded & will return to its
normal state when the concentration value goes back below the concentration set-point.
Even though the relay on the rear panel is a NON-Latching alarm & resets when the concentration goes
back below the alarm set point, the warning on the front panel of the instrument will remain latched until it is
cleared. You can clear the warning on the front panel by either pushing the CLR button on the front panel or
through the serial port.
In instruments that sample more than one gas type, there could be more than one gas type triggering the
Concentration 1 Alarm (“Alarm 2” Relay). For example, the GFC 7001EM instrument can monitor both CO &