Recent posts to PLC input timehttps://forge.codesys.com/forge/talk/Engineering/thread/09a1282525/2020-02-27T13:53:28.170000ZRecent posts to PLC input timePLC input time2020-02-27T13:53:28.170000Z2020-02-27T13:53:28.170000Zalwosohttps://forge.codesys.com/u/alwoso/https://forge.codesys.com6b0c685a21e44034d885561c820a741f28267768<div class="markdown_content"><p>Hi Dontjen!</p>
<p>It's always good to find your own solution that fits for the machine. And if you are new to PLC programming, don't hesitate - each problem has a chance in it </p>
<p>The OSCAT-library can be found here:<br/>
<a class="" href="http://www.oscat.de/dlmanager.html" rel="nofollow">http://www.oscat.de/dlmanager.html</a></p>
<p>There are several libraries available, just check the "Basic". There is a pdf manual for all functions, so you should find the necessary information. Maybe the FF_x blocks are helpful, or the LATCH_es.</p>
<p>Good luck!</p>
<p>Alfred</p></div>PLC input time2020-02-27T13:53:27.980000Z2020-02-27T13:53:27.980000ZDontjenhttps://forge.codesys.com/u/dontjen/https://forge.codesys.com43e49595b5401a690eae5baaf5fcb3614caecdee<div class="markdown_content"><blockquote>
<p><strong>alwoso hat geschrieben:</strong><br/>
Hi Dontjen!<br/>
Basically, a problem should be solved where it begins - hardware, software, material.....<br/>
Without knowing your application or hardware components, it's difficult to give the right answer. Ask yourself some questions to find out, which solution might be possible:<br/>
- How long is the part you want to detect in front of your sensor? Is it moving or standing still? Is the surface proper for this type of sensor?<br/>
- If it's only a short time, or if the part is moving: Is the input frequency of your sensor and the input-module high enough to catch the signal?<br/>
- If the plugs and connectors are the problem: Can they be fixed (e.g. to the machine body) or screwed together?<br/>
If you want to use some kind of timer in the software, you have to take into account, that this always means a delay in catching the signal. Your machine cycle might be extended!<br/>
The simple solution would be a "TON"-Timer, where the input signal triggers the timer and only if the signal is stable for the preset time, the timer-output will go high. But each flicker in the input signal will start the timer again - so your machine must stop and wait until you have a stable signal!<br/>
There are other solutions like filters - you look onto the signal for a number of cycles and if there are more than x HIGH-signals, you take this as a high on the input... and so on. That depends mainly on your programming experience and CPU-functionalities. You can find some functions in the OSCAT-library.<br/>
Good luck!<br/>
Alfred</p>
</blockquote>
<p>Thanks for the answer, delaying the input signal is not a real problem, the sensor is just there too see if there are parts present (multiple tiny parts in a container).<br/>
I'll check the hardware again next time (although i could not reproduce the error by wiggling wires etc etc, maybe the plc is so fast that it doesn't show...).<br/>
The oscat library is unknown too me, I'm new to plc programming.</p></div>PLC input time2020-02-27T13:53:27.411000Z2020-02-27T13:53:27.411000Zalwosohttps://forge.codesys.com/u/alwoso/https://forge.codesys.comda769e21e3e6c613513e8062ad83005161ccb762<div class="markdown_content"><p>Hi Dontjen!</p>
<p>Basically, a problem should be solved where it begins - hardware, software, material.....</p>
<p>Without knowing your application or hardware components, it's difficult to give the right answer. Ask yourself some questions to find out, which solution might be possible:<br/>
- How long is the part you want to detect in front of your sensor? Is it moving or standing still? Is the surface proper for this type of sensor?<br/>
- If it's only a short time, or if the part is moving: Is the input frequency of your sensor and the input-module high enough to catch the signal?<br/>
- If the plugs and connectors are the problem: Can they be fixed (e.g. to the machine body) or screwed together?</p>
<p>If you want to use some kind of timer in the software, you have to take into account, that this always means a delay in catching the signal. Your machine cycle might be extended!<br/>
The simple solution would be a "TON"-Timer, where the input signal triggers the timer and only if the signal is stable for the preset time, the timer-output will go high. But each flicker in the input signal will start the timer again - so your machine must stop and wait until you have a stable signal!<br/>
There are other solutions like filters - you look onto the signal for a number of cycles and if there are more than x HIGH-signals, you take this as a high on the input... and so on. That depends mainly on your programming experience and CPU-functionalities. You can find some functions in the OSCAT-library.</p>
<p>Good luck!</p>
<p>Alfred</p></div>PLC input time2020-02-27T13:53:27.222000Z2020-02-27T13:53:27.222000ZDontjenhttps://forge.codesys.com/u/dontjen/https://forge.codesys.comc4a014ff53efb17510e913deb507f052cb9eb71a<div class="markdown_content"><p>Hi,</p>
<p>My PLC has digital inputs connected to capacitive sensors. In my program I'm checking to see if it's detecting or not, <br/>
when it detects an object => everything is ok, continue etc. <br/>
When there is no detection it shows an error message on the HMI to the user and stops the machine.</p>
<p>Everything works like this but sometimes it shows the error when there is a object present. <br/>
I already changed the sensor to see if that was the problem. <br/>
I suspect it is from the vibration of the machine, the sensor is connected to the PLC over multiple connectors so if the <br/>
connector doen't fit good(age)/bad contact/old connector/.. or so => error</p>
<p>Is there a proper way to prevent this? Small timer on the input?</p></div>