I'm really puzzled why the input voltage range is only 0 - 10V, when the unit's power range is 12V - 24V. All of the switches / inputs / control signals I've seen in PLC boxes are the same as the DC supply voltage. If the Opta can't handle 12V inputs, I can't possibly use it.
You've not given very much information but maybe a voltage divider, consisting of two resistors per channel, may help bring the input voltage within the specification of the device.
Edit and fix broken link
Are you talking about this ? Hardware - Arduino Opta
Data sheet: https://docs.arduino.cc/hardware/opta
True, I can build additional hardware to fix the problem, but as much as I love this idea, virtually every other PLC on the market, including those powered by Raspberry Pi's, have digital inputs rated to the power input.
A pretty standard use case is a single AC/DC power supply in the cabinet outputting either 12V or 24V, since those are the standard voltages for both panel indicators and relays. An illuminated switch has (say) 12V running its lamp as well as being switch to turn on the relay. That control signal also runs to the PLC to control other things or to start monitoring.
With any other PLC I just connect the control voltage to an input. For Opta, I have to go design an additional circuit to make it work, and build it in such a way that it's rugged and DIN-mountable. Why would I work that hard?
Consider this a suggestion for the next generation which will make them infinitely more usable.
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Spot on!
I've just ordered a cheap Din rail PCB to do resistor divider & volt free sensing, feels like a retrograde step.
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I am pretty sure that 0 - 10 V only refers to the analog input range rather than the maximum input voltage for the digital inputs. The wiring diagram in the datasheet clearly shows them applying the supply voltage to the inputs.
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Hello!
For further clarification on this topic:
Inputs can be continuously operated at 24V without any issue as digital inputs. The only issue is that the VIH is set at around 5V so any voltage higher than that will be seen as high. On the other hand, when using analog any voltage over 10V would saturate.
Datasheets will be updated soon. Sorry for the confusion.
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This is the answer I was hoping for! One last clarification, does a digital out match the V+ voltage? As in, if this is powered by 24V, is the output voltage 24V as well?
Thanks!
The digital outputs are "dry contact" relay outputs, two terminal screws per output, one being the common and the other a normally-open output. So the voltage you get on the output will be the same as whatever you put on common side of the relay contact.
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