I have been tasked with adding user-adjustable delay timers to my ladder project. While I initially suggested using an HMI interface, they are looking for a simpler and more cost-effective solution. The M221 PLC has two built-in Analog inputs that can accept a 0-10V voltage range, which can be translated into adjustable time settings in the program. How can I find a knob that can be used for this purpose? It's not common to shop for a 0-10V knob, so I'm seeking advice on how to achieve this adjustability using a knob or alternative method. Thank you in advance for your help.
To regulate voltage around 24V, use a 10kohm potentiometer and a 14kohm resistor in series. According to Ohm's law, this setup allows for a 1mA current, so a power rating of 0.25W or 0.125W is sufficient. The resistor dissipates heat at 0.01W and 0.014W. Connect the center pin of the potentiometer to the analog input. If the voltage exceeds 24V, choose a resistor larger than 14kOhms to adjust the voltage in the range of 0-10Volts.
Thank you for sharing accurate data, it was very informative. Is there any risk of damage if the input exceeds 10 volts? My concern is the possibility of harming internal components. I worry that in the future, someone may increase the power supply from 24 volts to 26 volts without understanding the potential consequences. Hopefully, Schneider has built in a margin of safety for this voltage fluctuation.
gajtguy mentioned appreciation for providing actual values, stating that it was very helpful. Concerns were expressed about the potential consequences of exceeding 10v input, with worries about internal components being damaged. The fear of someone unknowingly changing the power supply from 24v to 26v in the future was also mentioned. It is hoped that Schneider has built-in protection against such voltage fluctuations. One possible solution suggested was to connect a zener diode with a voltage rating of around 10-11V in parallel with the input and a potentiometer to ensure the input voltage never exceeds 10-11V. It was noted that the zener diode has two different voltages, depending on how it is connected. Limiting the zener may not be necessary in this case.
User gajtguy expressed appreciation for the provided values and inquired about potential repercussions of exceeding a 10V input. There is concern regarding possible damage to internal components if the input voltage goes above 10V, especially if a power supply is inadvertently changed to a higher voltage like 26V. It is hoped that Schneider has built in some leeway for variations in voltage. I possess a voltage/current source device constructed by a fellow user using readily available components. You can search for it or message me for the details stored on my home drive. This device includes a schematic and parts list, and it is quite impressive. Regrettably, I cannot recall the creator. (0-10V, 4-20ma)
I appreciate your assistance. I am now about to purchase the necessary components and try implementing this solution for educational purposes. My customer has approved the HMI solution, so I will proceed with the project. Exciting!
Hi there! It sounds like you are looking for a potentiometer, which is a type of knob that changes resistance and can output 0-10V. They're not uncommon and you can usually find them at an electronics store or online retailers like Amazon or eBay. You want to make sure you choose one that can handle 10V and also make sure the resistance range matches your PLC's input range. Once you have the potentiometer installed, you can create a scale in your PLC program to translate the 0-10V input into your desired time delay range. Hope this helps!
You might want to consider using a potentiometer with a range that outputs a 0-10V signal; these are often referred to as voltage-divider pots. Check out industrial suppliers or online electronics retailers since they usually carry them. Make sure to choose one with a suitable resistance value for your needs—common values are around 10k to 100k ohms. Additionally, you could pair it with a simple op-amp circuit to ensure a stable 0-10V output, depending on your specific application. If you need a more straightforward solution, some manufacturers offer ready-made analog input devices that you can hook directly to your M221 PLC, which might save you time and ensure compatibility!
You might want to consider looking into rotary potentiometers that provide a variable output voltage, as they can be hooked up directly to your PLC's analog inputs. A typical 10K linear potentiometer could work well if you wire it correctly, giving you a smooth adjustability from 0-10V as you turn the knob. Additionally, if you go the potentiometer route, make sure to use a proper power supply for it, as well as a voltage divider if necessary, to ensure you're within that voltage range. If sourcing a potentiometer seems tricky, electronic component suppliers like Mouser or Digi-Key often have a good selection, and you can filter by resistance and output voltage. Good luck with your project!
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Answer: Answer: You can utilize the M221 PLC's built-in Analog inputs that accept a 0-10V voltage range to translate into adjustable time settings in your ladder program.
Answer: Answer: While it's not common to find a 0-10V knob, you can explore alternative methods to achieve adjustability, such as using a potentiometer or a rotary encoder.
Answer: Answer: By leveraging the Analog inputs of the M221 PLC and creatively using components like potentiometers or rotary encoders, you can achieve user-adjustable delay timers in a simpler and cost-effective manner.
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