P
RO
V
U
™ PD7000 Temperature Meter
Instruction Manual
26
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 meter 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.
•
In latching relay mode, if Fail-Safe is off, latched
relays will reset (unlatch) when power is cycled.
Non-Latching Relay (
Auto
)
In this application, the meter 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.
Automatic reset only
Condition
LED
Relay
Normal
Off
Off
Alarm
On
On
Ack (No effect)
On
On
Normal
Off
Off
Non-Latching Relay with Manual
Reset (
A-nman
)
In this application, the meter is set up for automatic
and manual reset at any time (non-latching relay).
The LED and the relay automatically reset when the
meter returns to the normal condition.
In addition, the relay can be manually reset while the
alarm condition still exists, but the LED will stay on
until the meter returns to the normal condition.
Aut manual reset at any time
Condition
LED
Relay
Normal
Off
Off
Alarm
On
On
Normal
Off
Off
Next Alarm
On
On
Ack
On
Off
Normal
Off
Off
Latching Relay (
LatcH
)
In this application, the meter is set up for manual
reset at any time. Acknowledging the alarm even if
the alarm condition is still present resets the relay and
turns off the LED.
Manual reset any time
Condition
LED
Relay
Normal
Off
Off
Alarm
On
On
Ack
Off
Off
