Precision Digital PD138 - Manual (Page 25)

PD138 Minimux
®
II Temp & Process Scanner Instruction Manual
25
Multiple Units
A system made up of multiple PD138s does not require any special
setup or programming. In fact, the model number is the same for all units
and they operate in the same manner as single units. There are several
terminals on each PD138 in the system that have to be connected
together, but this does not require a special cable. Instructions for these
connections are described in the Multiple PD138 Connections on page
15.
In a multiple unit system, the scan will progress through each channel on
the first PD138, move on to the first channel on the second PD138, scan
through its active channels and then move on to additional PD138s in
the same manner and then finally come back around to the first channel
of the first PD138.
Built-In Horn
Each PD138 has an independent built-in horn. In a multiple unit system
the built-in horn of the unit where the alarm condition occurred will
activate.
Alarm Relay
In a multiple unit system, only the alarm relay of the unit where the alarm
occurred will transfer. The user can wire the alarm relays for all units in
parallel to drive a single alarm device.
SILENCE, STOP/GO & ACK Buttons
Connecting the SILENCE, STOP/GO and ACK terminals at the rear of all
units in a multiple-unit system allows the operator to control and
acknowledge alarms from any unit in the system.
External SILENCE, STOP/GO & ACK Terminals
Connecting a N.O. pushbutton switch across all the STOP/GO & COM
terminals in a multiple-unit system allows the operator to control the
Minimux
®
II at a remote location. Connecting a N.O. push-button switch
across all the ACK & COM terminals in a multiple-input system allows
the operator to acknowledge alarms at a remote location. Connecting a
N.O. push-button switch across all the SILENCE & COM terminals in a
multiple-input system allows the operator to silence the PD138 at a
remote location.