ProtEX-MAX PD8-6060 Explosion-Proof Dual-Input Meter Instruction Manual
41
Latching Relay (
Lt-Clr
)
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 20).
When the ACK button or the assigned digital input is closed, all relays programmed for manual reset are
acknowledged.
Figure 19. Acknowledge Relays w/Function Key or Digital Input
+5
I1
I2
I3
I4
O1
O2
O3
O4
G
DO 1-4
GND
ACK
PDA1044 Digital I/O Module
1
2
3
4
5
6
7
8
9
10
DI 1-4
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
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