Special Signal modules
5-13
Programmable Logic Controllers S7-300 Module Data
A5E00105505-03
Ending the freeze function
The freeze function must be ended at every encoder input. You acknowledge the
function in the user program by setting the bit 0, 1 or 2 depending on the channel
with the STEP 7-Operation T PAB “xyz” (for a program example, see chapter
5.4.9).
After exiting, bit 31 of the corresponding encoder value is again deleted and the
encoder values are again updated. A renewed freezing of the encoder values is
again possible as soon as you have deleted the acknowledgment bit in the output
address of the module.
In synchronous operation the acknowledgment is processed at time T
o
. From this
point in time a renewed freezing of the encoder values can take place via the
digital inputs.
Note
The freeze function is automatically acknowledged if you newly parameterize the
corresponding channel with different parameters (see 5.4.8 chapter).
If the parameters remain identical, the freeze function remains unaffected.
5.4.8 SM 338; POS-INPUT Parameterization
You parameterize the SM 338; POS-INPUT with STEP 7. You must perform
parameter assignment in STOP mode of the CPU.
As soon as you have set all the parameters, download the parameters from the
programming device to the CPU. On a transition from STOP to ³ RUN mode, the
CPU then transfers the parameters to the SM 338.
The parameters cannot be changed by the user program.
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