Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 22)

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Channel Switches
ENA/DIS – Toggles the channel status between Disable / Enable / Alarm
ZERO – Press and release the ZERO button to zero the channel. Display will return to pre-set zero
level. The channel display to the immediate right of the channel display being zeroed will count
down the pre-set zero time out. (For Channel 4 the channel display immediately to the left will count
down the zero time out.) If zero level is reached within the pre-set time the channel display will read
don for “done.” If the zero level is not reached within the pre-set time the display will read err for
“error.”
Auto-Zero – Press and release the Zero button (< 1sec)
Manual Zero – Press and hold the zero button then push the up or down arrow buttons to
adjust the zero reading
Channel LEDs
Green (left) LED – Lights and remains lit when a probe is connected and the channel is enabled
(Non-Alarm mode). Lights and flashes when a probe is connected and the channel alarm is enabled.
(Alram Mode: Latching and non-latching.) LED remains flashing even as the Yellow, Warning and
Red, Alarm LEDs light during warning and alarm conditions.
Yellow (center) LED – Lights when the pre-set voltage warning level is reached. Remains lit until
voltage level drops below warning level (non-latching) or until the condition corrected and the
channel is reset (Latching).
Red (right) LED - Lights when the pre-set voltage alarm level is reached. Remains lit until voltage
level drops below warning level (non-latching) or until the condition corrected and the channel is
reset (Latching).
177A Relay and LED Functions
Initially all Ok, warning, alarm relays are closed (shorted or activated). The Ok LED is on; warning
and alarm LEDs are off.
Channel Ok relay is open (the green LED off) when:
 The channel is enabled and has no probe.
 The channel is disabled.
Channel Warning relay is open (the ember LED on) when:
The channel is enabled and the reading is on or above the warning level.
Channel Alarm relay is open (the red LED on) when:
 The channel is enabled and has no probe.
 The channel is enable and the reading is on or above the alarm level.
If the unit is in alarm latching mode and the reading comes back down, the relay will not close
until the [Ena/Dis] or [GRP] button is depressed.
System relay is normally closed. It is open when:
 One or more of the alarm relay is open.
 One or more of the enabled channel has no probe.
 Power supplies have failed.
Power LED:
On when the unit is powered up. Slow blink if power supply has failed.