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860-7200-18 DTU DTB Service & Maintenance Manual
OPERATOR PLATFORM MAT
The operator platform mat contains a sensor mat which detects
the presence of a person on the operator platform� The mat
senses pressure from the weight of a person and sends a 24VDC
signal to the PLC when there is sucient weight to activate it. The
mat circuit is normally Open circuit� There is an junction box on
the forward side of the operator platform, on the left side of the
machine� The box contains terminal connections for connecting
the two wires from the mat to a harness leading back to the PLC
inside this junction box� The mat is supplied by 24VDC from a
fuse� If the PLC does not receive a signal from the operator mat,
certain functions of the Destu-it will not work. The mat signal
must be received to reset the conveyor belts (Blue Reset light is
ON), to drive the Destu-it and to operate the hydraulics. If the
Destu-it conveyor belts are started with an operator on the mat,
the conveyor belts will shut o automatically after one minute if the
operator steps o of the platform.
SAFETY MATS
There are four safety mats on the sides of the Destu-it. There are
two large mats on either side of the Destu-it base frame beside
the front conveyor and two smaller mats on the steps of the base,
one on each side�
These four mats are wired in series with one another and are
monitored by the Safety relay� There are two separate circuits for
each mat� These circuits are Normally Closed� Stepping on any
one of the mats will activate the safety relay� The two separate
series circuits short together� The safety relay opens the three
contacts connected to the VFD and the VFD shuts o the Destu-
it conveyor motors� The VFD sends a signal to the PLC that a fault
has been detected� The PLC turns on the Fault light on the Control
panel and activates the beeper once every seven seconds� The
safety relay turns ON the Blue Reset light on the right-hand
mast� The belts can be restarted once the safety relay no longer
detects that something is on one of the safety mats and the Reset
procedure is done� The PLC controls a relay which closes contacts
on the Safety Relay to allow it to enable the belts�
To Reset the machine from a safety mat fault, ensure that nothing
is ON one of the four safety mats, stand on the operator platform,
turn the conveyor run/jog switch to the jog position for one second
and release. The blue Reset light on the right-hand mast will turn
OFF�
Operator Platform Mat
Platform Junction Box
Safety Mats
Safety Mat Relay
Reset Light (right mast)
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