SR FLIP FLOPS

[Rflower]

Hi all,

I am writing a S7 program that contains a couple of SR flip flops. When I try simulating by saving, downloading, monitoring and putting 

into RUN-P mode even before I turn on any input, the flip flop looks active.

Any ideas as to why this is happening?

 

Thanks for reading 

[Moggie]

One reason can be the use of the same address more than once or using a byte or word.

But without more details it is impossible to help, a screen shot would be useful

[Rflower]

Thanks for your reply. I did also consider your point and checked the addresses and they had no relation to the others. This happens when I haven't activated any input at all. Just putting the simulator in RUN-P causes this

The only way i have got around it is kept changing the address until it stops behaving like that. It may also be a software issue.

Here is a screen shot of one I'm currently having problems with.

 

I appreciate your response.

 

 

[Moggie]

Make sure MB0 is not used by the "clock" memory.

In the PLCSIM window show the status of MB0

[Rflower]

You are a star. I have now added the Memory BIT and when I did MB0.7 was ticked. I don't know why because I hadn't used that address previously.

I have now unticked it  as seen here. Thanks a lot Boss.

[Rflower]

I just didn't understand why it was ticked when I opened the MB when I hadn't used MB0.7 anywhere in the program.

 

 

Edited October 21, 2017 by Rflower
Needed to add more.

[Rflower]

3 hours ago, Moggie said:

Make sure MB0 is not used by the "clock" memory.

In the PLCSIM window show the status of MB0

Thanks very much Sir.