PLC5 to Logix conversion - FAL addressing

Hey everyone,

Just a question regarding the conversion of FAL element addressing between a PLC-5 and Logix5000-series processor. In the screenshot below, the addresses in the Expression field of the top FAL instruction in the PLC-5 are addressed to the specific word level, while in the Logix processor, they are indirectly addressed to [R6_003_POS]. I understand that this is the value of the .POS word of the control word R6[3], but is this the equivalent of using the "#" in #B22:0 to move from B22:0 through B22:3? In other words, I assume this is just going to go from B22[0] through B22[3] as the instruction evaluates according to the control word and length values.

I feel like I just talked myself through it and understand it better now, but this is my first experience with FAL instructions and seeing the indirect addressing threw me off a little bit.

Thanks in advance!

EDIT: Forgot to add the screenshot, d'oh!

After reviewing the Instruction Set manual for the PLC5, I'm fairly certain I figured out that I'm correct in my assumptions in the original post. It's just taking the binary values of B22[R6_003_POS], or B22[0] through B22[3], and AND-ing them with 21845, which is 0101010101010101 in binary and moving them into N7[R6_003_POS+6], or N7[6] through to N7[9]. The FAL instruction is actually fairly simple to figure out once I read the manual, go figure.

mylespetro, what you did looks good as long as R6_003_POS is an alias to R6_003.POS, etc. Otherwise you should change it to R6_003.POS & R6_004.POS in your FAL instructions.

RonJohn said:

mylespetro, what you did looks good as long as R6_003_POS is an alias to R6_003.POS, etc. Otherwise you should change it to R6_003.POS & R6_004.POS in your FAL instructions.

Click to expand...

Thanks Ron, looks like that is the case, screenshot below. This was created using the PLC5 to Logix5000 conversion utility, just realized I didn't say that in the original post.

Thanks again!