Novice needs help in repeating events

Hi all,

I need help in programing a evironmental chamber to vacuum and back fiil with gas (Purge).
In the first 3 hours,
Vacuum to 150 Torr
Purge with gas to 650 Torr
Repeat the above for a total of 3 times
Then maintain Pressure at 650T until the 3 hrs are up.

In the next 7 hours,
1. Vacuum to 150T
2. Purge to 650T
3. Wait 10 minutes

4. Vacuum to 150T
5. Purge to 650T
6. Wait 10 minutes

7. Vacuum to 150T
8. Purge to 650T
9. Full Vacuum for 30 minutes.

Repeat the above steps 1 thru 9 for a total of 3 times

After 7 hrs,
10. Purge to 650T
11. Vacuum to 150T
12. Purge to 650T
13. Vacuum to 150T
14. Purge to 750T

The Inputs ares:
I0:0.0/0 Start Mon Push Button
I0:0.0/1 Reset Program Mon Push button
I0:0.0/4 Program Selctor swicth

The Outputs are:
O0.0/0 Vacuum Vavle
O0:0/1 Purge Vavle
O0:0/2 Cycle One lite
O0:0/3 Cycle two Lite
O0:0/4 Cycle trhee Lite
O0:0/5 On lite
O0:0/6 Purge Lite
O0:0/7 Vacuum Lite

You've made an excellent start by defining all the steps in the sequence. It appears that you need sensors to indicate when the chamber is at 150, 650, and 750 Torr.

This could be a good application for a sequencer instruction if your PLC brand supports it.

Do you have a specific question?

Your project looks like a natural for a drum timer. Some of them are easy to work with - AutomationDirect.com for example. Others are difficult to set up and use.

To get you started, you can also consider using counters in conjunction with timers to keep track of which step you are on.

Do u use any pressure sensor to detect the vacuum pressure as your requir setting(150T, 650T & etc).If u are using a sensor which is an analog output then you need an analog input card to do the sequence u want. I think s7-200 series have the analog card u need.

Using Micrologix 1000 Analog and RSlogix 500

Have solved the analog input and scaled it to represent the pressure.
Store it in register N7:1
Just need help in doing the sequencing of these events

Sequencer

Here is a link to some sample sequencer programs.HERE

I agree with Tom Jenkins that a drum timer on the Automation Direct plc would be easier.

Well Mike It looks like you have every thing in hand,

Here is a simplified version of what I do in sequencers.

Hope this gives you the peice you are missing.

Old threads never die (as long as the old server doesn't)

Here's two old threads of mine on creating a generic sequencer, with code examples. These basically follow the same type of logic that Allan's does, and are easier to implement than the SQO instruction.

http://www.plcs.net/dcforum/DCForumID1/2402.html#12

http://www.plcs.net/dcforum/DCForumID1/2313.html#4

These should get you started. If you've got any more questions about these, feel free to ask.

Thanks to everyone who replyed.
I believe that I have got it.

I will post my results for the group to critique.

BR

Mike