ProtEX PD8-6080/PD8-6081 Explosion-Proof Modbus
®
Scanner Instruction Manual
48
Relay Action for Communications Break (
break
)
The Scanner will poll the slave device three times before reporting a communications break condition.
After the third failure, the Response Timeout timer starts and will determine the actual time to report a PV
in break condition.
1. Turn
On
(Go to alarm condition)
2. Turn
Off
(Go to non-alarm condition)
3. No Action (The relays will maintain the last condition)
Relay Action for Loss of 4-20 mA Input (Loop Break)
The loop break feature is associated with the 4-20 mA input. Each relay may be programmed to go to one
of the above conditions when the scanner detects the loss of the input signal (i.e. < 0.005 mA).
Notes:
1. This is not dependent on the Communications Break or Response Timeout setting.
2. This is not a true loop break condition; if the signal drops below 0.005 mA, it is interpreted as a
“loop break” condition.
Relay and Alarm Operation Diagrams
The following graphs illustrate the operation of the relays, status LEDs, and ACK button.
High Alarm Operation (Set > Reset)
For Manual reset mode, ACK can be pressed
anytime to turn "off" relay. To detect a new alarm
condition, the signal must go below the set point,
and then go above it.
Low Alarm Operation (Set < Reset)
For Manual reset mode, ACK can be pressed
anytime to turn "off" relay. For relay to turn back
"on", signal must go above set point, and then go
below it.
