Large Display Temperature Meters
Instruction Manual
34
Alarm Setup and Set Points Programming
Overview
The Digital Temperature Meter is available with four alarm points and
corresponding front panel status LEDs as a standard feature. The front panel
LEDs are useful for alarm applications that require visual notification only. For
applications that require relay contacts, such as driving external alarm devices or
on/off temperature control, the Digital Temperature Meter can be equipped with
either two or four relays. Any of these relays may be assigned to set and reset at
predetermined temperatures. Each relay can be set up for latching or non-
latching operation independently.
Programming the relays involves four steps:
1. Setting the relay manual reset (ACK enable) jumpers.
These jumpers (JP5) are located on the Display PCB and determine if a
relay can be manually reset.
2. Setting the fail-safe jumper (J5).
Fail-safe mode (default): In the alarm condition, the NC contacts are
connected to the Common (C) contacts of the relays. The fail-safe operation
can be disabled, by removing jumper J5 located on the Options PCB.
3. Setting the alarm set points for latching or non-latching relay operation using
SETuP
menu.
4. Setting set and reset points using
SEtPtS
menu.
a. Setting set points for alarms.
b. Setting reset points for alarms.
Set Relays for Manual or Automatic Reset
Jumper array JP5 located on the Display PCB is used to program the relays so
they can be reset manually. For location of JP5 on the Display PCB, see:
Figure 34 on page 63 for PD755.
Figure 35 on page 63 for PD756.
Figure 36 on page 64 for PD757.
Set Relays for Fail-Safe Operation
In fail-safe mode, the relay coils are
energized
and the Normally Open (NO)
contacts are connected to the Common (C) contacts under normal operation.
During an alarm condition, the relay coils are
de-energized,
the Normally Closed
(NC) contacts are connected to the Common (C) contacts. During power failure,
the relay contacts reflect an alarm condition.
Removing jumper J5 disables the fail-safe operation. J5 is located on the Options
PCB next to the J2 connector. For location of J5 on the Options PCB, see:
Figure 24 on page 57 for PD755
Figure 25 on page 58 for PD756
Figure 27 on page 59 for PD757
If fail-safe mode is disabled, operation of the relay contacts is opposite to the
one described in the previous paragraph.
