Systems can be engineered to allow multiple operators to control one crane on a first-come, first-serve basis – for
example, two to three operators working one piece of equipment using ‘Pitch and Catch’; two operators
simultaneously controlling a single decoder; or one operator with a supervisory control overriding the second
operator with all or selected functions.
A variety of proportional (motion stepless) systems are available for the Cattron MP96 system. The preferred
Cattron standard is Six Motion Stepless. This is a six motion proportional system with a choice of high current, low
current or Pulse Width Modulation (PWM) load drive capabilities. It should be noted that the MP96 series may be
configured for up to 10 Motion Stepless systems, although limited auxiliary functions would be available in such a
configuration. In addition to the ‘volt free’ potentiometer, all ‘stepless’ systems have ‘ON/OFF’ outputs for each
direction (forward/reverse). These models include integral transfer relays for the analog output selection from
manual to remote control. For additional information regarding proportional (stepless) systems, please refer to
Proportional Systems later in this section.
4.5.1 Fault-Tolerant Operation
The MP96 has the ability to detect a failure in the controlled machine and still provide limited, safe, continued
operations.
In addition to the mainline power contactor, various machine functions can be separated and placed in up to six
individual motor groups. This allows the MP96 to ‘shut down’ a failed area of the machine (e.g., trolley) and still
allow operation of other functions (e.g., hoist and bridge).
4.5.2 Protocol
One important safety feature is the use of a unique Cattron intelligent digital message protocol for industrial
control applications rather than the customary Electronic Data Processing (EDP) type of message format. Only
the unique, digital data message generated by a Cattron controller transmitter will be recognized; all others are
rejected. This special protocol is complex and consists of start bits, synchronization, address, command and
error-checking bits. The information must be received and decoded correctly at least twice a second or the
decoder outputs will stop.
4.5.3 Decoder Circuit Board
The decoder is the programmable computer portion of the Cattron MP96 system. It provides simultaneous and
independent output functions according to commands from the correct operator controller.
4.5.4 Multiple Microcomputers
The MP96's single board decoder employs three microcomputers interfaced with various I/O devices for
maintaining safety and integrity of system functions. The first of these is the control microcomputer which is
tasked with all I/O functions and message traffic and is responsible for Operate (OPR) Relay #1 and the motor
group main contactors.
The secondary microcomputer is responsible for the additional verification of the received messages of the
control microcomputer. When a transmitted command message is received by the decoder, it is verified by the
control microcomputer and passed to the secondary microcomputer. Additionally, this same command message
is directly routed to the secondary microcomputer which then independently verifies the proper address and
returns it to the control microcomputer for comparison and final verification. The secondary microcomputer is also
responsible for the OPR #2 operational commands. The two OPRs, in series, control the equipment mainline
contactor.
The third microcomputer is the data microcomputer. It is dedicated to the handling of data processing and storage
for later recall, using the status display and datalog analysis utility program.
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