Precision Digital PD6080 - Manual (Page 61)

PD6080/PD6081 Super Snooper Modbus Scanner Instruction Manual
61
Front Panel LEDs
The LEDs on the front panel provide status indication for the following:
LED Status LED Status
1 Alarm 1 5 Alarm 5
2 Alarm 2 6 Alarm 6
3 Alarm 3 7 Alarm 7
4 Alarm 4 8 Alarm 8
The scanner is supplied with four alarm points that include front panel LEDs to indicate alarm conditions.
This standard feature is particularly useful for alarm applications that require visual-only indication. The
LEDs are controlled by the set and reset points programmed by the user. When the display reaches a set
point for a high or low alarm, the corresponding alarm LED will turn on. When the display returns to the
reset point the LED will go off. The front panel LEDs respond differently for latching and non-latching
relays.
For non-latching relays, the LED is always off during normal condition and always on during alarm
condition, regardless of the state of the relay (e.g. Relay acknowledged after alarm condition).
For latching relays, the alarm LEDs reflect the status of the relays, regardless of the alarm condition. The
following tables illustrate how the alarm LEDs function in relation to the relays and the acknowledge
button (Default: F3 key assigned to ACK):
Latching and Non-Latching Relay Operation
The relays can be set up for latching (manual reset) or non-latching (automatic reset) operation.
Relay terminology for following tables
Terminology Relay Condition
On Alarm (Tripped)
Off Normal (Reset)
Ack Acknowledged
The On and Off terminology does not refer to the status of the relay’s coil, which depends on the fail-safe
mode selected.
Warning!
In latching relay mode, latched relays will reset (unlatch)
when power is cycled.
Non-Latching Relay (Auto)
Automatic reset only
Condition LED Relay
Normal Off Off
Alarm On On
Ack (No effect) On On
Normal Off Off
In this application, the scanner is set up for automatic reset (non-latching relay). Acknowledging the alarm
while it is still present has no effect on either the LED or the relay. When the alarm finally goes away, the
relay automatically resets and the LED also goes off.