Bit Shift from AB ML to Siemens S7-300 and 400

[Paradigm_shift]

Good morning everybody.


Sirs, I have a problem when converting a shift logic from a AB ML processor to a Siemens S7-300.

The program is based on a sensor that verifies if there is a product on the input conveyor of the machine. When the product is caught by the sensor, a brake is released. In AB I used just to use a BSL with a negative edge signal from my sensor. When the sensor lose the signal from the box (OSF) I set a B3:0/0 and when my encoder performs a "n" number of pulses I shift that bit and reset it.

On Siemens, I'm not getting how can I do the same logic, when I get the negative edge I set a bit and when my encoder goes "n" pulses I shift that bit to the left and reset that bit.

Please Siemens experts, if you can, post it on ladder, 'cause I'm not that good on STL or SCL.

I'm sending a pic with my AB logic.

If anyone could help it'd be very helpful, thx since now.

 

[KalleOlsen]

Hi!

You'll find the instructions in the catalog:

Bit logic/ NEG = negativ edge detector
Shift/Rotate / SHL_W = Shifs a word (16 bits) left by chosen value.
Comparator / GE_I = Compare an integer if greater or equal
Highlight and push F1 for more info.

Kalle

 

[Paradigm_shift]

Actually I'm not getting how to make the logic, the functions I already knew them

I'm not finding a way to set the bit and shift it. On AB I set that bit a shift it on the other word, but on siemens, when I try to do the same logic, everytime the bit is lost, I'd like to memorize the shifted bit every time I shift the next

 

[KalleOlsen]

Do you want a bit to reset after n turns? What is then the purpose of the shifting?

Kalle

 

[L D[AR2P#0.0]]

Here's an example implementation showing the shift register after two shifts:

 

[KalleOlsen]

I don't know AB, but could it be he's gone into the little/big-endian trap?

 

[Paradigm_shift]

Thanks L D[AR2,P#0.0], I'm not with my work notebook in hands, but after the weekend I'll test it to check if it works well, but anyway thanks for the help.

Kalle, what I want is to set the bit when the carton leave the input conveyor then shift it to the left, but the conveyor doesn't have products all the time, and the machine' motor keeps rotating, and the carton keeps going ahead inside the machine, so I need to reset that bit every time my encoder performs 1 turn and shift just the products that are already inside the machine.

 

[KalleOlsen]

NOW I understand. I live in a cold place so the brain spins slowly...

Kalle

 

[L D[AR2P#0.0]]

.... I'll test it to check if it works well,

Post your original code so we can exaplin why it does not work.

 

[Paradigm_shift]

I think that what I did wrong was to use the M0.0 and M0.1 as the pulses. If Siemens works like AB, the negative and the positive edge signal needs two auxiliars to work, am I right?

 

[Paradigm_shift]

Actually where is written MW1 on the BSL_W is MW10.

 

[Paradigm_shift]

But now, I don't know why, when the bits reach the 7th bit and I shift them again, the 7th bit isn't shifted to the 8th bit.