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S5-115U Manual
Direct Signal Status Display "STATUS VAR"
Use the "STATUS VAR" test function to indicate the state of a random operand (input, output,
flag, data word, counter, or timer) at the end of a program scan. The information is taken from
the process image of the operands in question. During Program Check or in the "STOP" mode, the
state of the input modules is read in directly for inputs. Otherwise, only the process image of the
operands that were called is displayed.
4.3.5
FORCE Outputs and Variables
"FORCE" Outputs
You can set outputs to a specific signal state directly without using the control program. Use this
direct method to check the wiring and functioning of output modules. This procedure does not
change the process image but it does cancel the output disable state.
Note
For the "FORCE" test function, the PLC must be either set to the Program Check
function or in the "STOP" mode. The function must only be executed without the load
voltage.
"FORCE" Variables
With the "FORCE VAR" test function, the process image of binary and digital operands is modified
regardless of the PLC mode.
The following variables can be modified: I, Q, F, T, C, and D.
Program scanning with the modified process variables is executed in the "RUN" mode. However,
the variables can be modified again in the remaining program run, without a checkback signal.
Process variables are forced asynchronously to the program run.
Special characteristics include the following:
•
Modify the variables I, Q, and F only by bytes or by words in the process image.
•
For the variables T and C in the KM and KH format, proceed as follows:
-
Enter a "Y" in the SYS. OPS. input field in the presets menu.
-
Pay particular attention to forcing of edge trigger flags.
•
An incorrect format or operand input interrupts the signal status display. The system outputs
the message "NO FORCE POSSIBLE".
EWA 4NEB 811 6130-02b
PLC System Start-Up and Program Test
4-11
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