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CONNECTION TO EXTERNAL CONTROLS
The controller offers interconnection points for external controls and indicators. This allows simple connection to
remote controls and indicators, or integration into any plant-wide controls system.
Remote On / Off
- Remote on-off control of the system requires only a simple two-wire control, with an isolated
contact suitable for 120 volts, 1 amp. This may be a switch, a timer contact, a relay contact, or a PLC output. To
connect, simply run the two wires to the control enclosure, remove the jumper between terminal 6 and terminal 9 on
the terminal strip, and connect the two wires to terminal 6 and terminal 9.
The air compressor will operate normally in its selected mode whenever this contact is closed (turned on). Note that
the keypad is always the master control; the operating mode must be selected at the keypad, and the remote is not
capable of starting a unit after the [STOP/RESET] key has been pressed to place the controller in the READY state.
When the contact is opened (turned off), operation depends on how the controller has been programmed and what it
is doing prior to opening the contact.
If the compressor was already stopped in automatic or sequence modes, it will remain stopped and will not restart
until the contact is closed. The display will flash the message
"REMOTE HALT"
to indicate that it is waiting for the
remote signal.
If the compressor was running in any mode when the contact was opened, and the remote response is programmed
for
"IMMEDIATE"
, the compressor will immediately unload, and will run only until the reservoir is blown down. Then
the motors stop, and the unit will be in the
"REMOTE HALT"
mode as indicated above.
If the compressor was running in any mode when the contact was opened, and the remote response is programmed
for
"TIMED UNLOAD"
, the compressor will immediately unload and blowdown. It will then continue to run unloaded
for whatever period has been programmed for
"AUTO TIME"
(or will complete the remaining auto time if already
blown down). The controller displays
"REMOTE UNLOAD"
during this period. After completion, the motors will stop,
and the unit will be in the
"REMOTE HALT"
mode as indicated above.
When the remote is turned back on, the unit will start immediately in the CONSTANT or LOW DEMAND modes.
Loading in these modes, or starting in AUTO or SEQUENCE modes will occur when the pressure drops below the set
pressure.
Alarm Relay -
The controller is provided with an alarm relay which may be connected to a remote mounted indicator
light, horn, or into a PLC input of a plantwide control system. The contact is commercial rated 2 amps at 120 volts.
The relay is turned on whenever there is a SHUTDOWN condition requiring service at the compressor, and remains
off during normal operation, stopping, or power off conditions. The external connections from the controller are from
an isolated form C (single-pole, double-throw) contact. This allows control of either a "compressor okay" or a
"compressor shutdown" remote indicator.
To use this relay, connect the supply wire for the remote circuit to terminal 21 (relay common) on the terminal strip.
Connect a wire to the indicator from either terminal 19 (normally open) or from terminal 20 (normally closed).
Connect the other side of the indicator to its neutral.
Serial Communications -
The RS-232 port is available for serial communications of compressor data to external
monitoring systems at any time. If units are NOT connected in sequence, the RS-485 port may be used for multi-
drop communications of compressor data to external monitoring systems. Data available include all pressures and
temperatures, and a report of internal service data. This is accessible with a PC or PLC with an appropriate
communications port. For protocol information, request drawing 305EAU1255.
Wiring Diagrams -
The following wiring diagrams show connections in typical units. Refer to the wiring diagram
shipped with the compressor unit for actual connections.
Summary of Contents for AUTO SENTRY-ES+
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