Step 7 IEC timer not working ,Help!

[PLC_talk]

I am facing a strange problem.
I have built a simple SFB4 TON being turned on by a bit M80.0 & with a fixed time of T#5S. (Seperate DB instance created) As soon as I put the bit M80.0 on the Q bit M81.0 also get ON . Both are not used anywhere in logic.I am using s7-PLCSIM v5.3-SP1 .
Can anyone throw some light on this.
Thanks

 

[ivo.maenen]

There should be a problem with PLC-SIM and IEC-timers according to this post:


http://www.plctalk.net/qanda/showthread.php?t=27565&highlight=plcsim

But 10BaseT. has a solution for it.

 

[PLC_talk]

Thanks Ivo. Actually the reason I started on the IEC timers is that I am having S7H redundant system. In one of siemens manual I read that S5 standard timers will not work in redundant system, Is this correct? I don't have access to h/w at present, but have to test everything on Sim.

I got all my ladder ready with S5 timers & now I am running out of time to figure a solution for IEC timer if they r a must.
pleaase advice.

Thanks