I'm experimenting with Opta (after buying the PLC Starter Kit).
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As a PLC newbie, but with experience on Arduino and microcontrollers in general, I was surprised seeing how to connect a button input, directly, without any pull-down or pull-up resistors. Does the Opta have internal not configurable pull-down resistors or something similar?
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I'm familiar with 5v and 3.3v power. Is operating with 24v safe, even if I touch the terminals?
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What happens if I connect 24v input to an input of the Opta set as analog (that should accept 0-10v for analog signals)?
Thanks.
24vdc has become the standard in industrial controls automation. That said, i wouldnt go out of my way to touch it, out of good habits, but it is safe, that is one of the reasons for switching from 120vac to 24vdc controls.
I doubt the Opta is internally protected, so its likely it would blow out that pin. just keep in mind that your analog devices can in a lot of dfferent styles, 0-5vdc, 0-10vdc, 4-20mA, 0-20mA, just to name a few. so if you have a mA transmitter you will need to either put in an external resistor to convert it to a voltage signal, or get a 5 dollar milliamp to voltage convertor board.
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I would think being touted as industrial, if you have the input set to Analog and input a digital +24… the input should be fine…. However, i have no clue??
- You need to ask Arduino support in an email (not forum).
- If you have a lot of money, and can afford another OPTA, test this out yourself and play with it a little.
Hello,
Here's what I can do for you:
- When you configure an input as Digital Input, the Opta internal circuit gives a low state when the voltage is below 4.46 VDC and a high state when the voltage is above 6.6 VDC. Between the two the state is unstable and cannot be guaranteed.
- There is no risk of electric shock with a voltage of 24 VDC. It becomes dangerous above 48 VDC.
- According to this comment the only problem is that it saturates above 10V.