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Pulsar2003

1760-L12AWA

6 posts in this topic

I have a project with a small heated press. There are two buttons to start the press. As it is quite old the buttons are large stainless steel square protected by a funnel like shape. The problem is that one can leave a heavy object resting on one and only use one to start the cycle. I could also look up to find the kind of sensors that detect the presence of a finger and when it does it goes on or sends a signal to an automated systems As I have an unused Pico I was wondering if I could use it for security purpose? Unfortunately these relays don't have the One Shot possibility. I was wondering if I could use a timers with a very brief time to simulate the one shot. This means that both timers would need to be reset to start the cycle again. Each timers would have a dedicated input. As for the cycle it is simple enough, as simple pneumatic actuator activates a mechanism that multiplies it's power to perform a 3 Ton pressure on a die that make a imprint on fabric. The pressure is done only a few seconds and the air is released and the die goes up. That's it. Let see what some of you experts can come up with. Thanks.

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It's not clear to me what you want to do with a one-shot, but this is how you make one without a one-shot instruction. see picture.

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The Pico controllers have a "rising edge" option for the Coil instruction that serves the same function as a one-shot with an ordinary OTE after it. There are also other simple ways, like the one Mickey illustrated, to get a one-shot function out of a simple controller. But what you're talking about is a "two hand anti-tie-down" control for a press. These kinds of controls are very common on presses, shears, and other sorts of machinery that are hazardous to operate with your hands too near. If you're re-doing the controls on the press, you are generally obligated to perform a risk assessment and determine if you need a "safety-rated" two-hand anti-tie-down controller and special touch buttons, or if an ordinary general purpose relay or programmable relay can be used. I admit I'm not familiar enough with the OSHA or CSA requirements for doing that kind of analysis. If you decide to use this small controller and your existing pushbuttons, here's an example of two-hand anti-tie-down logic, posted here on MrPLC: http://www.mrplc.com/kb/index.php?article=13

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Ken's suggested link is the correct direction. I echo his statements concerning a safety risk assessment. I did the same logic for a two hand control pendant to jog a shaft driven machine. The output was used to engage/disengage a clutch. The clutch was also SIL 3 device and could also lock it self out. Just goof around a little with the timer preset to get a more realistic expectation of a reasonable time to press both buttons within. OSHA has some values...memory seems to say something like 0.5 secs or less.

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Hello Mickey I simply want to prevent anyone from modifying the functions of the press, in this case is to lock one of the safety switch from being blocked on the ON position and using only the other button to start it. Having a one shot would do the job because both switches have to go again as a 0 in order to reactivate the press. The tips have been useful. I will have to ponder on it and see what can be purchased if I can have a budget. Thanks to you all.

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Does the 1760-AWA meet ANSI B11.1 and OSHA 1910.217 Standards

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