Mitsubishi Electric WS0-CPU0 Operating Manual page 242

Chapter 9
Figure 225:
Overrun monitoring with the
Universal press contact
function block
Note
239
Logic programming – Function blocks
Overrun monitoring
If the Overrun cam input is enabled, the Universal press contact function block
monitors the overrunning of the press, i.e. it checks whether the Overrun cam cam is
left although the press is expected to have stopped.
The Drive released input signal must then accord with Figure 225 and the following
rule.
At the Drive released input there has to be either a Low to High transition between
the Low-High transition of the Top output and the end of Overrun cam (High-Low
transition), or the Drive released input has to be High at the end of the Overrun cam
(High-Low transition). If none of these two conditions is fulfilled, the Enable output
becomes Low and the Overrun error output becomes High.
The Drive released input must be connected to the signal that controls the physical
output of the press drive, so that the function block can determine whether the press is
currently supposed to be running or has been stopped. Typically this is the Enable
output of a subsequent Press setup or Press single stroke function block.
Do not connect any physical input signals to the Drive released input. Connect the
signal that controls the physical output for the press drive using a jump address or a
CPU marker.
 If a jump address is used, make sure that this signal is a loop-back. This is
indicated by a clock icon on the destination tag of the jump address. To this
purpose, connect the outputs of this function block to the following function blocks
before you connect the jump address to the Drive released input. This applies
especially if all connections to the following function blocks are also realized using
jump addresses.
 If a CPU marker is used, then a Routing function block must be used to split the
signal to the physical output for the press drive and to the CPU marker output.
Disable monitoring
Using this optional input it is possible to deactivate the monitoring functionality under
certain conditions in order to prevent the function block to go into an error state. This
can be useful for certain operating modes, e.g. during the setup of the machine or
when the press moves backwards.
If the Disable monitoring input is High, the Enable output of the Universal press
contact function block is Low and the monitoring of the cam signal sequence and
overrun is inhibited, provided there is no error pending. The error output states are not
affected by this.
If the Disable monitoring input is High and an error is pending, a reset of the error is
possible.
When the Disable monitoring input changes from High to Low, the function block
behaves in the same way as after a change from the Stop state to the Run state, i.e.
the Enable output will become High again.