latched timer by a pulse

Iam useing modsoft and i have a problem
when an pneumatic cylinder advances and retracts i need to latch a timer to blow air on our product
CYLINDER FORWARD
CYLINDER RETRACT
SOLENOID BLOW ON LATCHED FOR A SET TIME
I am not a complete beginner
I would really appricate some help

Others may correct me but this doesnt look to hard, do you have MRS (magnetic reed switches) on the cylinder OR a way to detect it has retracted, if so then use that to initiate a timer.

NOW if you dont have MRS then all is not lost there are many ways to do this. The activation of the retract cylinder output can initiate a timer sequence.

You didnt state what brand plc you are working with and the minor details, I reckon thats why many havent answered the post.

Ask again but this time give more details and post what you have tried.

As Ron indiates, you have to have some kind of limit switch to indicate the cyclinder is retracted. Then you can use the very common "Holding" circuit to actuate the solenoid. You'll have to flesh out the details yourself, but this should get you started:

|

|  Retracted      T1        Lockout

|----| |-----+----|/|----------(C0)

|            |

|    C0      |

|----| |-----+

|

|   Retracted   T1           Blow-Off

|----| |--------|/|------------(Y1)

|

|    C0

|----| |----------------------|TMR

|                             |T1

|

|   Retracted    Lockout      Extend

|----| |----------|/|---------(Y0)

James:

Use care when implementing the above code. You said you are using Modsoft, which probably means a 984 processor. If so, remember that it scans differently than most "normal" PLCs. The -|/|- Lockout bit on rung 4 must be to the right of the Lockout -( )- coil on rung 1, otherwise you will extend while you blow-off, which is probably not what you want.

(I'm sorry, Tom. You probably did that deliberately, as an "exersize for the reader', and here I come barging in and spoil it).

Actually, Allen, I just forgot that the "old" 984 instructions scan differently. I haven't done any Modicon for a while! We have a project "on the boards" now using Modicon, but we are going to the IEC-1131-3 compatible "Concept" software just to avoid this kind of problem.