Mitsubishi Electric WS0-CPU0 - Page 239

Chapter 9
236
Logic programming – Function blocks
TDC monitoring
There must be exactly one TDC pulse per cycle. A violation of this rule can be
detected only if the Overrun cam input is enabled and/or the BDC input is enabled
and the parameter Number of BDC signals per cycle is set to 1 (e.g eccentric press).
Overrun cam monitoring
If Overrun cam is enabled, the Overrun cam input signals must accord with Figure
221 and the following rules:
There must be exactly one Overrun cam pulse per cycle. The rising edge of the
Overrun cam input (Low-High transition) must occur before the falling edge of the
TDC input. The falling edge of the Overrun cam input (High-Low transition) must
occur after the rising edge of the TDC input. This means that at any time at least one
of both inputs must be High.
BDC monitoring
If BDC is enabled and Overrun cam is disabled, the BDC input signals must accord
with Figure 222 and the following rules.
(1) The beginning of the BDC (Low-High transition) must be close to 180° and has to
occur while the TDC input is High.
(2) The end of the BDC (High-Low transition) has to occur before the rising edge
(Low-High transition) of the TDC input. In other words, BDC must be Low when a
Low-High transition at the TDC input occurs.
Figure 221:
Contact monitoring with the
Universal press contact
function block with Overrun
cam enabled
Figure 222:
Contact monitoring with the
Universal press contact
function block with BDC
enabled