Science Buddies: "Ask an Expert"

Hello, I have a PLC that I was playing around with for a while, I tested it out by running a simple program, which was a ladder logic to make a sequence flasher, however, this flasher was based on 2 relays that where controlled by inbuild functions;

|-----| | X001 ----------------|/| M8012----------------(Y010)-|


|-----| | X002-----------------|/|M8013----------------(Y011)-|
|-----------------------------------------------[END]---------------|

M8012 is a preprogrammed 10 millisecond on/off, with a looping sequence
M8013 is a preprogrammed 1 second on/off, with a looping sequence
X are inputs
Y are outputs,
this was wired so that every second, the 10 mS pulse function would be turned on/off.
and I shot a little video of that: http://www.youtube.com/watch?v=t3qdaCBUxKM

I am still a newbie and have not mastered ladder logic yet, so the question bieng, has anyone here worked with PLCs before? and if so,
how does one program it to turn a relay on and off at irregular times (say 3 seconds pass, and turned on, then 5 seconds later turned off) since there are no preset commands, and a function must be writen, so I would like that if someone could perhaps either explain to me how this is done, or could point me to a book about it,
also, for reference, this is a Mitsubishi FX2N series programmable logic controller.

I would appreciate any help that anyone can offer, thank you for your time.

I'm not experienced with PLCs, but I had a quick look at the programming guide available on the Mitsubishi web site. Do you have this? It's at:
https://my.mitsubishi-automation.com/do ... &sstr=FX2N

In Section 2.5.1, it shows how to set timers and counters, in the ladder logic context. This looks like what you would need if you wanted to program in your own time intervals. (However, that's just my initial guess here!)

Hope this is of some help.