GE Series 90 Micro

[Golfman 0]

Hi I am new to this site and need some help with the GE instruction set.. Most all my plc experience has been with Allen Bradley ( PLC 5, SLC 500, and Micro Logix ) but now I have some GE stuff. I under stand the GE programming language, but I really need help with the shift register instruction. Here is what I am trying to do. I need to be able to track parts ( part present / not present ) down a conveyor till they get to the next application. Now this may not be a good example. So if you have a better scenario please feel free to use it as an example. Any help will be greatly appreciated..

[RussB 22]

It is best to get that kind of assistance from the online help of Proficy ME. Put a function block that you need in ladder, select it and press F1. That will take you right to all of your answers, if there is anything there that you do not understand, ask here.

[Golfman 0]

I have read the online help file in versa pro, but do not understand how to set up the shift register. IN B2 N Q B1 LEN I can set it up the way I think it is susposed to be but when make the shift happen it will only shift the bit one time. I can not get it to cascade.. 1111101111101111. I know it can be done but I just not doing it right..

[Steve Bailey 118]

The instruction you have chosen may not be the best fit for what you're trying to accomplish. In the first place, the "LEN" parameter defines the number of sixteen-bit words over which the shift operates. The "IN" node defines the starting address. When the logic at the upper left hand node of the function is true, the bit pattern in the word will be shifted by the number of places defined at the "N" node. The logic at the "B1" node defines whether a 1 or 0 gets shifted in. The "Q" node defines the staring address of the shifted bit pattern. For your application, this should be the same address as the "IN" node. The "B2" node tells you whether a 0 or 1 was the last bit shifted out. You should also take a look at the SHFR_BIT instruction, found in the "DATA MOVE" group of functions. This allows you to define the specific number of bits over which the shift operates, rather than the number of sixteen-bit words. It also has a "Reset node to drive all bits to zero.

[Golfman 0]

Thanks for the info Steve, but I am still am having trouble. With allen bradley you can use a BSL Instruction to shift individual bits to the left and you can track their status through the word.. Can you do this with GE? If so what would be the best instruction for my application.. Thanks Jody