2 Operating principle
Blocking Protection for Pumps with SIMOCODE pro V
Article ID: 109478058, V2.0, 09/2020
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2.2.6
Reversal in the opposite direction when conveying fault has been
detected
The output of the timer is set with the value "true" at output 1 of truth table TT9,
which is fed into the input plug of Timer 1. The timer is parameterized as an
opening delay. The delay time to be programmed is the time that the drive is
supposed to run in the opposite direction; it should be chosen depending on the
application. The output of the timer is connected via truth table TT7 with the "ON<"
plug of the "Protection/Control" function block for this purpose.
At the same time, the motion command in the conveying direction is rescinded via
truth table TT2. This also causes the interference signal at the output of truth table
TT9, and thus the input of the timer, switches back to "false". The motor will now
continue turning in the opposite direction until the time runs out, as long as it is not
reset before that time via its Reset plug.
Once the timer expires, its output switches back to "false", causing the "ON<"
command to be rescinded via TT7, while the "ON>" command is issued again via
TT2.
A requirement for this logic to function is the parameterization of the operating
mode "Save change-over command".
2.2.7
Fault shutdown after defined number of reversals
For every positive edge of the interference signal at output 1 of truth table TT9,
Counter 1 is incremented. It thus counts the times that the motor runs in the
opposite direction. If the counter reaches its programmed limit (in the application
example n=4), the drive will have already gone through n-1 reversals (in the
application example 3) and the counter output "Q" is set to "true". This triggers the
External fault 1, which causes the drive to be switched off and generates a
corresponding error message.
2.2.8
Drive start after fault shutdown
As with any fault, the "External fault 1" error message generated by the function
block after the logic has detected it must be acknowledged. Therefore, it only
possible to start the drive again after the fault has been acknowledged.
Acknowledgement is only possible after resetting Counter 1. This is done through
truth tables TT3 and TT6 by performing one of the following actions:
•
Test/Reset button on the SIMOCODE basic unit is pressed ("Test/Reset
button" socket of the "BU inputs" function block)
•
Test/Reset button on the SIMOCODE operator panel is pressed ("Test/Reset
button" socket of the "OP buttons" function block)
•
Acknowledgment via a PLC (socket for bit 6 of the function block "Cyclic
receive Byte 0")
