analogue module

Table 5.9: 0-20 mA and 4-20 mA analog values.

As you are using the PIWxxx address directly, you will be accessing a decimal value between 0-27648 for an acceptable signal, in the rated range.
If your analogue input module is setup for 4-20 mA current input, a value of decimal 1 in your comparator will give you immediately a signal thal you are just over 4 mA (I would set it up a bit, as a deadband value to block any unwanted fluctuating signals).
If you are setup for 0-20 mA, then a value of 4 MA would be equivalent to decimal 5530 (or thereabout, if you enter a deadband, again).

Hope this helps,
Daniel Chartier