HIMA HIQuad X - Forcing

Programming System
Page 82 of 110 HI 803 211 E Rev. 1.01.00
6.2 Forcing
Forcing is the procedure by which a variable's current value is replaced with a force value.
The current value of a variable is assigned from one of the following sources:
 A physical input.
 Communication.
 A logic operation.
When a variable is being forced, its value is defined by the user.
Forcing can be used in the following cases:
 For testing the user program; in particular, in cases or conditions that cannot otherwise be
tested.
 For simulating unavailable sensors when the initial values are not appropriate.
WARNING
Physical injury due to forced values is possible!
 Only force values after receiving consent from the test authority responsible for the
acceptance test.
 Only remove existing forcing restrictions with the consent of the test authority
responsible for the acceptance test.
When forcing values, the person in charge must take further technical and organizational
measures to ensure that the process is sufficiently monitored in terms of safety. HIMA
recommends setting a time limit for the forcing procedure, refer to Chapter 6.2.1 for details.
WARNING
Failure of safety-related operation possible due to forced values!
 Forced value may lead to incorrect output values.
 Forcing prolongs the cycle time. This can cause the watchdog time to be exceeded.
Forcing is only permitted after receiving consent from the test authority responsible for
the acceptance test.
Forcing can operate at two levels:
 Global forcing: Global variables are forced for all applications.
 Local forcing: Values of local variables are forced for an individual user program.