String Comparison in Mitsubishi FX3U PLC?

Hello all,

I need to compare the first three digits of a barcode string to a known value.

I have the string being pulled from the Serial buffer, and placed into memory.

I found the instruction " $= " in the GX Works 2 help as a string comparison. But it seems like the FX3U PLC does not support this instruction.

If I can't use the string comparison, what are my alternatives to compare these values?

If I can't use the string comparison, what are my alternatives to compare these values?

Click to expand...

I did not look up the manual for the FX3U, but the usual alternatives for manipulating strings are:
(1) use a string or ASCII instruction that extracts (separates) the first 3 characters and places them into a new string, or
(2) use a string instruction that searches the string for certain characters, or
(3) use a string instruction that compares two strings, AND
(4) use a string instruction that converts a string to an integer number value, AND
(5) compare the new number value to a known value, using a EQUAL, LESS THAN, or GREATER THAN comparison instruction.

Look in your PLC Help file (or your PLC programming manual) for string or available ASCII instructions.