Detcon 840 - Manual (Page 21)

840 Operators Manual
Model 840 Operator Manual Rev. 1.9 Page 17 of 29
6.6 Alarm Test Mode
Alarm conditions can be simulated and relay contacts can be verified by use of this special software
feature. To activate the Alarm Test Mode, hold the z (Down) key for 5 seconds while in the Main Display
Mode. After holding the z (Down) key for 5 seconds there will be an audible “Chirp”, then all active gas
channels will display “CH# 00 TESTING”. The readings will increment up at 1% full scale per second.
When full scale is reached, the readings will decrement to 0. The unit will continue to cycle until Alarm
Test Mode is exited. As the readings cross their respective alarm set points, the relays will fire according to
their configuration. To exit Alarm Test Mode, hold the z (Down) key for 5 seconds and the unit will
return to Normal Operation.
6.7 Display Contrast
The display contrast can be adjusted by pressing the “up-arrow” key when the unit is in Normal Operation.
Pressing the “up-arrow” key repeatedly will cause the display contrast to change in steps to the minimum
limit; the contrast will then ‘roll’ back to the maximum limit and start the cycle over. When the correct
contrast level is obtained stop pressing the “up-arrow” key and the contrast will remain at that level.