MC³ 24.96.EX O&M Manual
Page 4
08/14/01 4:34 PM/LDD
Backplane Board
Most of the Digital I/O connections to the MC³ will be made through the Backplane Board. The
Backplane mounts vertically in the rear access cover on the Panel mount type enclosure. On the
Wall mount enclosure, the boards are mounted directly below the Card stack assembly. The
boards can also be mounted onto a DIN rail away from the controller. The Backplane Board has 7
output relays and 4 input connectors and allows connection to one I/O rack on the PCIO card. This
board connects to the PCIO card via a ribbon cable.
Additional Backplane boards may be connected using a DIN rail as the mounting for the boards.
Up to four Backplane boards may be connected to the MC³ Controller when two PCIO boards are
in the card stack assembly.
Card Stack Assembly
The Card Stack assembly consists of a CPU Board, one or two PCAD boards, one or two PCIO
boards and an LTI board. The Card Stack Assembly in the panel mount enclosure is mounted to
the slide tray and is kept in place by a pair of guides that are permanently mounted onto the
enclosure and catch screws on the back of the enclosure. In the wall mount enclosure the Card
Stack Assembly is securely attached to the mounting plate. All boards are connected electronically
by way of an industry standard PC-104 interface bus.
CPU Board
The CPU Board contains the Intel 386EX Microprocessor. It also contains associated support
circuitry for a bus interface, serial interface and memory support. The CPU board is the bottom
board of the card stack.
PCAD Board
The Load Cell Transducer A/D Board (PCAD) contains the circuitry needed to process an input
from load cells into digital data. The Analog to Digital Converter used on the PCAD Board is a 20
bit converter. This allows the Analog Load Cell signal to be resolved into approximately 1,000,000
digital counts. As an option, the 2496EX Controller has the ability to utilize two PCAD boards.
There are no switches on the PCAD Board for setting parameters such as Gain, Zero Offset or
Electronic Calibration. The PCAD Board contains specialized circuitry for dynamically adjusting
these parameters through software. There is one set of jumpers to select Zener Barrier Protection
and Normal Operation of the PCAD.
PCIO Board
The PCIO Board provides the circuitry for two isolated analog outputs, one isolated analog input,
16 digital outputs and 8 digital inputs. The standard MC³ 2496EX Controller comes with one PCIO
board. One additional PCIO Board is available as an option giving the controller a capability of
having four isolated Analog Outputs, two isolated Analog Inputs, 32 Digital outputs and 16 Digital
inputs. There are two racks of inputs and outputs per PCIO board. Each rack consists of 7
outputs and 4 inputs. Each rack is connected to a Backplane board via a ribbon cable.
LTI Board
The LTI (LCD Tachometer Input) Board contains the circuitry required to process incoming speed
pulses from one or two Tachos, outputs for an AC and DC Electromechanical Totalizer (EMT), an
isolated RS-485 Serial Port and an interface to the Display assembly.
The RS-485 Serial Communications port is a feature which provides the circuitry necessary for the
MC³ Controller to communicate with other serial devices such as a SuperBridge or Personal
Computer. For more information on MC³ Serial Communications see [1] This specification lists
some hardware options and interconnection examples and also describes the Merrick
Communications Protocol in detail.
Power Supply Assembly
The Power Supply Board provides the proper voltages to the MC³ for operation. The Power
Assembly consists of the Power Supply, Power Receptacle and an AC and DC power cables. The
Power Supply is mounted on the front of the slide tray.
