I always set the number of pulses as a data memory address so it can be changed from the operator interface. Looking at the programming manual it appears than you have to set it up that way.
When you look at an instruction reference in an Omron programming manual it lets you know what king of addresses you can use.
The N parameter for the PULS instruction on indicates only memory areas (IR, SR, AR, DM, EM, HR, LR) meaning it must be referenced to a memory area not a constant.
The reference for the F parameter in the SPED instuction shows (IR, SR, AR, DM, EM, HR, LR, #) as the possible values. The # means that a constant can be set as well as a memory area.
I don't remember if you will see the LED pulsing on the output point or not. We use the Omron CJ1 for that machine now so it has been awile since I have looked at it.