Monitoring and outputs
Reference Manual
June 2016
MAN-0076, Revision 09
34
Monitoring and outputs
The fault detection circuitry does not monitor the operation of external response equipment or
external wiring to the transmitter. It is important that external equipment and wiring be checked
periodically to ensure they are operational.
6.7
Fault conditions
Fault conditions will override any alarm conditions because the sensor may be unable to detect a gas
exposure reliably, as such, the alarm relay will not provide an output.
Fault conditions provided by an instrumentation device are critical indicators that the device is not
operating as expected; therefore, when a fault condition is present, immediate attention to that fault
condition is required.
Net Safety strongly recommends that the 2.5
mA analog fault condition and fault relay (if used) be
monitored in conjunction with alarm levels on the analog output and the alarm relay, if used.
6.7.1
Transmitter fault conditions
Fault conditions that the transmitter detects are as follows:
Fault condition
M21
M22
Input voltage less than 8
VDC
P
P
Input voltage more than 33
VDC
P
P
Critical memory fault
P
P
Onboard power supply fault
P
P