User guide

Multi Process Meter Instruction Manual
58
Latching Relay (Lt-Clr)
Manual reset only after alarm condition has cleared
Condition LED Relay
Normal Off Off
Alarm On On
Ack (No effect) On On
Normal On On
Ack Off Off
In this application, the meter is set up for manual reset only after the
signal passes the reset point (alarm condition has cleared).
Acknowledging the alarm while it is still present has no effect on either
the LED or the relay. When the alarm is acknowledged after it returns to
the normal state, the LED and the relay go off. Notice that the LED
remains on, even after the meter returns to the normal condition. This is
because, for latching relays, the alarm LED reflects the status of the
relay, regardless of the alarm condition.
Acknowledging Relays
There are two ways to acknowledge relays programmed for manual
reset:
1. Via the programmable front panel function keys F1-F3 (Default:
F3 assigned to ACK).
2. Remotely via a normally open pushbutton wired across one of
the digital inputs and the +5 V terminals on the digital I/O
modules, or using the F4 digital input, which is triggered with a
contact closure to COM, or with an active low signal (see page
23).
When the ACK button or the assigned digital input is closed, all relays
programmed for manual reset are acknowledged.
Figure 21. Acknowledge Relays w/Function Key or Digital Input
+5
I1 I2 I3 I4
O1 O2 O3 O4 G
DO 1-4
GND
A
CK
PMA-12 Digital I/O Module
1 2 3456 7 8 9 10
DI 1-4