Large Display Temperature Meters
Instruction Manual
30
ENTER Button Functionality
The
ENTER
button is used to program the meter for various functions, is located
on the Display PCB and is labeled SW2. The
ENTER
button on PD755 can be
accessed from the front panel. The
ENTER
button on models 756 and 757 can
only be accessed with the front panel removed. The
ENTER
button can also be
accessed by wiring a normally open pushbutton switch across terminals EN and
CM on connector J1 located on the Main PCB (see Figure 7 on page 26).
ACK Button Functionality
The
ACK
button is used to acknowledge the relays when the meter is in reading
mode and to quit the menu scroll in programming or diagnostic. If
ENTER
has
been pressed and the meter is scrolling down the menu, pressing
ACK
button
returns meter to reading mode, it does not acknowledge relays during menu
scroll.
Magnetic Reed Switch Functionality
The PD756 has two magnetic reed switches located above the
ENTER
and
ACK
buttons. The reed switches allow the user to program and operate the meter
without having to remove the enclosure cover.
To operate the reed switches, move the magnet assembly (PDA-MAG) toward
and away from the glass window, just above the
ENTER
and
ACK
buttons. The
action is detected when the magnet is moved away from the glass window.
Moving the magnet toward and away from the glass window produces the same
results as pressing the front panel buttons.
The PD756 can be programmed and operated in three different ways:
1. Using front panel push buttons.
2. Using external push buttons wired to J1 connector. Explosion-proof control
stations are required when used in a hazardous area.
3. Using magnet assembly to operate the reed switches.
PDA-MAG (Optional)
Move magnet toward and away
from cover to operate ENTER
and ACK buttons
Magnet
Handle
Figure 12. Reed Switch Operation
