Onboard Diagnostics - Macurco CM-12 User Instructions

Selecting Trouble Fan Setting Option – "tFS"
To select the Trouble Fan Setting Option, in normal mode, push the Next button to get to "Con" or the Configuration menu. Then
push the Enter button to enter the Con menu. The eleventh selection is the "tFS" or Trouble Fan Setting Option. Push Next ten times
to get to "tFS" then Enter. If Trouble Fan Setting is "OFF" push Next to turn it to "ON" (flashing) then push Enter to confirm the change
(solid) and push Enter again to return to "tFS" in the Con menu. Push Next until "End" is displayed then push Enter to get back to
normal operation.
Selecting 4-20mA Output Option – "420"
To select the 4-20mA Output Option, in normal mode, push the Next button to get to "Con" or the Configuration menu. Then push the
Enter button to enter the Con menu. The twelfth selection is the "420" or 4-20mA Output Option. Push Next eleven times to get to
"420" then Enter. If the 4-20mA is "On" push Next to turn it to "OFF" (flashing) then push Enter to confirm the change (solid) and push
Enter again to return to "420" in the Con menu. Push Next until "End" is displayed then push Enter to get back to normal operation.

Onboard Diagnostics

The CM-12 monitors all critical functions of the unit through software diagnostics that continuously test and verify unit operations. If a
problem is found, the unit will switch to a fail-safe/error mode or trouble condition. In this error mode, the Alarm relay will be activated,
the 4-20 mA current loop will go to 24 mA, the unit will display the error code, the green status indicator LED light will flash and the
buzzer will chirp intermittently. The Fan relay will also engage if the Trouble Fan Setting Option is set to "ON". This is a safety
precaution. To clear this mode, simply turn off power to the unit for a few seconds, or push the ENTER/TEST switch (inside the unit).
This will cause the unit to restart the 1 minute self-test cycle.
The 4-20 mA signal can be used for troubleshooting:

0 mA is most likely a connection problem

4-20 mA is normal gas reading range (0-200 ppm)

24 mA indicates a Trouble condition
Error Codes

t01

t02

t04

t08

t10

t20

t40

t80

t100

t200
Sensor missing
Temperature compensation failure
EEPROM bad checksum
Sensor is shorted
Bad EEPROM
Bad calibration
Factory calibration failure
Read ADC failure
Under range
Sensor expired
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