Easy RSLogix 5k question

I am brand new to Allen Bradley programming, my background is with GE Fanuc.

Basically what I am trying to accomplish is to OR a BYTE.

I have a 16pt discrete input card. The first 8 inputs and the last 8 inputs are identical. The difference is they are created from different power sources is the reason for duplicating the inputs.

So logically what I want to do is OR those 8 bits together such that if either input is high, the result will be high.

I could do this with parallel contacts and a coil, but that would be a very time consuming and error-prone solution given the number of inputs on this system.

My best attempt was to copy 8 bools to two SINT registers and OR the SINT registers, but copy doesn't like the mismatched type when I try something like ENGINE:2.I.Data.8 to grab the last byte.

I would create an intermediate INT tag, then perform a Swap Bytes command to copy the Engine:2:I.Data tag to that intermediate tag in Low/High byte order.

You might need a Masked Move in there, too, if you want to treat the result as an 8-bit only data value.

Take a look at the Boolean Exclusive Or(BXOR) and Bitwise Exclusive Or(XOR) instructions; one of them might just be what you need.

I'm not 100% on what you are trying to do but I would look in the Move\Logical tab in the ladder editor. There are few functions in there that help with BIT operations in BTYES.

Ken Roach said:

I would create an intermediate INT tag, then perform a Swap Bytes command to copy the Engine:2:I.Data tag to that intermediate tag in Low/High byte order.

You might need a Masked Move in there, too, if you want to treat the result as an 8-bit only data value.

Click to expand...

This looks like exactly what I want. Thanks!