operating 12 solenoids with a single timer

Hi
Thanks for the supports given by the forum.

now, i would like to operate 12 solenoids in a sequential, one after another in auto mode. the time for each solenoid is set through the hmi. Setting 12 time is difficult so, i like to set a single time for the entire 12 solenoids. how can we do this?

Thanks
Ron

Hi,
Forgot to say, i am using Automation direct DL-250-1 PLC

You can keep the 12 timers. They can all use the same V memory value as a preset.

Why not a time based drum? Even the cheapest PLC's have a drum instruction, plus you gain the ability to run in auto or be able to set inputs to jog through the drum cycle.

If you don't want / can't use a drum, you could use a single timer to run the time, then compare contacts for each solenoid based on the time that it should cycle. If your time base was in seconds, you could do something like

12 = TD1 --------- Y1

15 = TD1 --------- Y2

and so on. If the first output (Y1) needs to cycle at 12 seconds, when 12 = TD1 (Timer data), Y1 activates, and on down the line.

There are probably ***ier ways to do it, but that's how I would do it if I wasn't using a drum.

Actually, re-reading this, I missed the part about setting time through a HMI.

Are you setting the time before the cycle starts, or the time between the solenoid actuations? Is the time between solenoids the same between 1-2, 2-3, 3-4, etc?

Brandon_K said:

Why not a time based drum? Even the cheapest PLC's have a drum instruction, plus you gain the ability to run in auto or be able to set inputs to jog through the drum cycle.

Click to expand...

Could you elaborate on what a drum instruction is please. I have not seen one in Logix 500 or 5000.

passwordg said:

Could you elaborate on what a drum instruction is please. I have not seen one in Logix 500 or 5000.

Click to expand...

For Allen-Bradley PLCs : Drum = SQO

Hi
I'm also thinking these two options, 12 timers, and a single V memory as well as the drum.
time should be set before the cycle startup. I haven't yet used this drum instruction. could anyone explore this?
I went through the help instructions, though, any help will be appreciated highly.



Thanks
Ron

Hi ,
I have finalized the operation sequence now, which has 23 steps (on and off of solenoids). A drum can have 16 steps. is it possible in a drum instruction?

Thanks,
Ron

Rather than a drum I would just set up a counter as a sequencer - say, CT0 - with a preset of 24 and pulse it with SP4 (if all you need is whole second resolution). Do a compare statement to determine which steps you'd like each solenoid to be energized.

I don't know why people use the drum instruction when a sequencer is so much simpler and more powerful to use.