Detcon DM-200 - Manual (Page 25)

Model DM-200
DM-200 Instruction Manual Rev. 2.0 Page 21 of 40
Missing Sensor
If the ISM is missing or not connected properly, the UTM will report “Missing Sensor” and an output of 1.0
mA will be set.
Memory Fault
If new data points cannot successfully be retrieved from memory the display will indicate: “Memory Fault”.
Comm Error
If the ISM and UTM are not communicating properly, then the UTM will report “Comm Error”.
4. Service and Maintenance
4.1 Exchanging the ISM
A key feature of the UniTox™ product is its complete universality (exchangeability) between any combination
of ISM and UTM. The ISM carries all necessary identification and parameter data stored in permanent
memory, which allows for any ISM to instantly begin seamless operation with any UTM.
4.1.1 Physical Exchange
In order to remove an ISM, the user should twist the retaining collar in a counter clockwise direction. When
the threads are cleared, the ISM should be pulled straight out. To reinstall the ISM, first view the mating gold
pin pattern until proper alignment is achieved. Then press in the ISM until mechanical surfaces touch.
Finally, move the retaining collar up and thread clockwise until snug.
NOTE: Remember to twist the retaining collar tight after successful ISM/UTM
communication is established. The collar should tighten snugly up to the mating surface in
order to create a water tight seal. Never grab the ISM main housing and attempt to twist. This
may damage the gold pin connections.
4.1.2 Establishing Communication
The UTM will display "Missing Sensor" during time when the ISM is not connected. When an ISM is
disconnected from a UTM, the end-user must wait approximately 7 seconds before another ISM can be
plugged into the UTM. This 7 second period is the time required by the UTM to reach the "ready-to-receive"
state.
After plugging an ISM into the UTM, within 1-3 seconds the ISM identification/parameter information will be
displayed and at the conclusion of the data string a "Returning to Normal Operation" message will be
shown. If for some reason the ISM identification/parameter information does not come up after 10 seconds,
then unplug the ISM and repeat the process again after 10 seconds.
4.1.3 Maintaining "Biased" ISM’s using the Battery Back-up Module (Optional)
When and How to Use
Some electrochemical sensors are biased with an excitation voltage. When power to the ISM is lost, this bias
voltage slowly decays. When power is restored after long periods (multiple hours) of being un-powered, a
surge in sensor output takes place and a long and slow re-establishing of the sensor’s zero baseline takes place.
This re-stabilization time may range from 1 hour to 24 hours depending on the type of sensor and range of
operation. The sensor types that this applies to are the following: HCl, NO, plus all the VOC sensors, C2H30,