Mitsubishi Electric WS0-CPU0 Operating Manual page 173

Note
Figure 153:
Logic example for two
cascaded Switch
synchronization function
blocks
Notes
Note
Logic programming – Function blocks
Cascading mode – with cascade input
Several Switch synchronization function blocks can be combined to a cascade so that
all outputs will be switched at precisely the same time.
By cascading multiple Switch synchronization function blocks it is possible to
synchronize more than six inputs. If the function block is configured with Cascade
input, the Cascade output is present additionally.
All cascaded function blocks must be configured with the same Hold time for outputs.
All Cascade output signals must be connected back to the Cascade inputs of all
used Switch synchronization function blocks via an OR function block and a CPU
marker (see also Figure 153).
 Do not use a jump address for the back routing of the cascade signal but a CPU
marker. This ensures that all related Switch synchronization function blocks will
process the signal at the same logic cycle.
 The timer is increased by the necessary value to compensate the delay resulting
from the connection of the Cascade input via the CPU marker.
A rising edge on the Cascade input starts the timer (timer start value is the system
time from the last logic execution cycle). When the timer has elapsed, the values of
the inputs 1A to 3B at this point of time are applied to output 1A to 3B, irrespective of
the result of the antivalence check. The outputs keep these values until the next
synchronization process occurs.
Antivalence check
If this function is enabled, an antivalence check is performed every time when the
Hold time for outputs has elapsed (i.e. every time when the outputs take the current
input values). If any of the used input pairs Input 1A/Input 1B to Input 3A/Input 3B
does not have antivalent values (i.e. one input of each pair must be Low and the other
input must be High), then the Antivalence error output changes to High. It becomes
Low again when another synchronization process has been finished without an
antivalence error. The behaviour of the outputs 1A to 3B however is independent of
the result of the antivalence check.
In order to obtain a defined output value combination in case of an antivalence error,
the Error output combination function block can be used (see Chapter 9.8.11).
Behaviour on startup
On transition from the Stop state to the Run state, the outputs will be set immediately
according to the input values and the antivalence check will be executed, if configured.
In this case the function block does not wait for the Hold time for outputs to expire.
Chapter 9
170