Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 21)

20
Rear Panel Relay Connections
Three status LEDs and relays are assigned to each channel. These LEDs and relays are referenced
as OK, WARNING, and ALARM. External monitoring equipment can be connected to these via
screw terminals located on the rear panel of the instrument. Connections are specified in Figure 7
on page 10 and on the instrument’s cover.
Three modes of operation are available:
Alarm Mode - Latching
Under normal operating conditions (i.e. the monitored static level is less than the preset
warning and alarm levels) all three relays are energized initiating a contact closure. The
green or OK status LED is blinking while the yellow or WARNING and red or ALARM status
LEDs are not lit.
When static levels reach the preset Warning level and the preset Alarm Delay has expired
(refer to Program Setup in Section 9 for details) the Warning relay will open and the Warning
LED will light. The OK LED will continue to blink. Whenever the instrument achieves
Warning mode it will stay in that condition until the problem is corrected or the static level
falls to less than the preset warning.
When static levels reach the preset Alarm level and the preset Alarm Delay has expired
(refer to Program Setup in Section 9 for details) the Alarm relay will open and the Alarm LED
will light. The OK LED will continue to blink and the Warning LED remains lit as well.
System Alarm - Upon realization of an alarm condition the System Alarm relay will open.
Upon opening the System button on the Monitor screen on your pc will flash red.
Whenever the instrument achieves Alarm mode it will stay in that condition until the problem
is corrected and the instrument is manually reset by toggling the channel’s ENA/DIS button
on the instrument console or via the pc program provided or by momentarily shorting the
Alarm Reset terminals on the back panel.
Alarm Mode – Non-Latching
Under normal operating conditions (i.e. the monitored static level is less than the preset
warning and alarm levels) all three relays are energized initiating a contact closure. The
green or OK status LED is blinking while the yellow or WARNING and red or ALARM status
LEDs are not lit.
When static levels reach the preset Warning level and the preset Alarm Delay has expired
(refer to Program Setup in Section 9 for details) the Warning relay will open and the Warning
LED will light. The OK LED will continue to blink. Whenever the instrument achieves
Warning mode it will stay in that condition until the problem is corrected or the static level
falls to less than the preset warning level.
When static levels reach the preset Alarm level and the preset Alarm Delay has expired
(refer to Program Setup in Section 9 for details) the Alarm relay will open and the Alarm LED
will light. The OK LED will continue to blink and the Warning LED remains lit as well.
System Alarm - Upon realization of an alarm condition the System Alarm relay will open.
Upon opening the System button on the Monitor screen on your pc will flash red.
Whenever the instrument achieves Alarm mode it will stay it that condition until the static
level falls to less than the preset warning level resetting to normal operation.
Non-Alarm Mode
In non-alarm mode the alarms are disabled, the green or OK remains lit continuously.
Warning and Alarm are not triggered. The instrument continues to monitor static levels
regardless of operating conditions.