Model MCX-32
Model MCX-32 Instruction Manual
Rev. 2.3
Page 3 of 49
1.2.3
Auxiliary Relays
The Interface PCA contains two relays that can be configured and used for contact closure outputs for
‘FAULT’ and ‘NO-COMM’ errors. The Fault Relay is set whenever there is a sensor fault, and the No-Comm
relay is set when there is a no communication error. These relays are configurable as to how they will be set
when a fault or no communication error occurs. The relays may be configured as Energized or De-energized,
Silence or Non Silence, and Latched or Unlatched. This allows a great deal of flexibility for setting these
relays up as needed. Refer to section 6.3.2 RL4 Setup Screen for the configuration of the relays.
1.2.4
Auxiliary 24VDC input
The MCX-32 has the ability to operate on the internal 24VDC power supply, or on the auxiliary 24VDC input.
This auxiliary 24VDC input can be an external 24VDC power source, a battery backup unit, or it can be
directly wired to a set of batteries. The input source (rated at 20 to 30VDC) should be capable of delivering up
to 5Amps continuous current.
The Interface PCA will monitor both the primary internal 24VDC power
supply, and the secondary auxiliary 24VDC input. Should the primary internal 24VDC power supply stop
functioning or fall below 18VDC, and the secondary auxiliary 24VDC input is still operational, the controller
will automatically switch to the secondary input.
If batteries are connected to the auxiliary 24VDC input, the Interface PCA has the unique ability to provide a
nominal 27VDC at about 1Amp specifically for charging the batteries. This voltage is only to be used for
charging batteries. Damage may result if this charging voltage is enabled and the input voltage source is not
batteries (See Section 6.3.9).
WARNING:
Switching the secondary from DC POWER to BATTERY with a hard line DC power
source connected to the Auxiliary 24VDC Input may result in damage to the MCX-32 and other
electronic equipment.
Do not change the secondary source to BATTERY unless batteries are
connected to the controller.
1.3 Programming Configuration
The MCX-32 controller can be configured for various I/O combinations at the Detcon factory based on
application specific information provided by the customer on the Configuration Form. It must be verified that
the correct quantity and type of I/O modules have been purchased to support the customer’s configuration
requirements. On the Configuration Form, the customer should supply all site-specific information:
1) Number of gas channels
2) Detcon sensor model number and I/O type (Modbus
™
or 4-20mA) for each channel
3) Range, units, and gas type for each channel
4) Alarm level(s) for each gas channel
5) Tag Name for each channel
6) Assignment and set-up information for each relay contact
7) Analog output requirements for each channel
NOTE:
The set-up configuration is fully field-programmable and can be executed by the user
in the field. Refer to Section 7.0 Controller Setup. Modifications to the set-up configuration
are expected to take place at the customer’s site due to requirement changes and/or system
expansions.
