PLC flashing alarm light or output

Hi,
I am trying to make an A-B SLC 500 operate a solenoid which in turn operates a cylinder, and would like to get a flashing light when the cylinder does not fully extend after a specified time period, and the same light to stay on when it does extend fully and activate the prox switch. I need to do this with 5 different cylinders in the the same process. Any help would be appreciated, some spelling help wouldn't hurt me either. Ooooops, I am using RSLogix.

Many thanks,
Zero1954

Here is a brief example:

Hi Kim,

Thanks very much for the info, I was doing that part of the ladder differently, but like your way a little better. The part I don't remember (I've been in production management the last 5 years) is how to make the out put flash on and off. I thought I had to use a counter in a sub-routine.

Thanks much,
zero1954

Use a 1 second timer. Once programed you can use it for many applications. I've also seen the PLC clock used.

I thought I had to use a counter in a sub-routine.

Click to expand...

Zero, you might have missed one thing in Kim's post. The S:4/5 bit in kim's ladder example is flashed AUTOMATICALLY by the plc at a 50% duty cycle (i.e. on and off times are the same). As her description states, the rate on that bit is 640 msec (=0.64 sec).

The word at S:4 in the SLC status file is the free running clock in the processor. Basically it is a counter that is incremented by 1 every 10 msec automatically by the processor. The effect is that S:4/0 is on for 10 msec and then off for 10 msec then on etc... Due to the way binary counting works, each higher number bit is flashed on/off for double the time of the previous bit. So, S:4/1 is on for 20 msec, off for 20 msec. S:4/2 ... 40 msec on/40msec off.

The exact rate of flashing a light is not usually critical so using one of these built in flashing bits can save you time.
If you need a specific rate that does not line up with the "doubling" rates in the free running clock then you would need to create your own timer and logic to look at it.