Siemens S7 M0.0 1

[simisteven]

Can somebody please explain what M 0.0 is ?
thanks

 

[CanadianTaff]

Its an internal memory bit.

M 0.0 is the least significant bit of the byte MB0

 

[simisteven]

Thanks CT. But does m 0.0 have any special function in S7 eg does it pulse on and off every X milliseconds?
In the program I am using, M0.0 is read only not written

 

[CanadianTaff]

My bet it is used as the clock pulse, MB0 is the default for this and enabled in the CPU properties in the hardware profile.

Each bit from M0.0 through to M0.7 will switch at a different frequency.

Bit of the Clock
Memory Byte 7 6 5 4 3 2 1 0
Period Duration (s) 2.0 1.6 1.0 0.8 0.5 0.4 0.2 0.1
Frequency (Hz) 0.5 0.625 1 1.25 2 2.5 5 10

 

[CanadianTaff]

Bit of the Clock
Memory Byte Period Duration (s) Frequency (Hz)
7 2.0 0.5
6 1.6 0.625
5 1.0 1
4 0.8 1.25
3 0.5 2
2 0.4 2.5
1 0.2 5
0 0.1 10

Hope that shows a bit better, so M0.0 would be a 10Hz clock bit (100mS cycle).

It only does this if enables in the CPU properties and the byte used can be changed from the default byte 0.

 

[simisteven]

gotcha now, Thanks CT