The Industrial Raspberry Pi Forum

Hi,

im trying to control Digital Outputs of RevPi Compact via Node-Red. Have 7 different valves - valve 1 (DUutBit_1) - valve 6 (DOutBit_6) are controlled true/false by different conditions, its working fine with every valve. Parallel valve 7 (DOitBit_7) should be on with every valve of 1-6 in parallel (flow attached). Its absolutely not clear why DOutBit_7 is only switching in parall whe valve 6 is true. in node-red editor its shown that valve 7 is true parallel to valve 1-6 but Hardware in reality is only switching when valve 6 is true...
Thanks for help in advance!
Best
Gunnar

Well Gunnar, my thoughts on this is something I remember from studying called digital logic. So you can create a truth table according to the boolean logic of your desired application.
The truth table then covers the simplest available logic to implement the necessary application that fits your requirements. I have googled around, and maybe this page or similar ones can guide you:
http://www.32x8.com/index.html

I'm not so experienced in Node-RED, but perhaps it is better to implement it in the form of just having an output once instead of multiple times.
Likewise, Pin 7 can be triggered by six different other nodes. Perhaps this is why the truth table cannot be implemented, as the output Pin 7 can be switched by various preconditions simultaneously

Thanks Dirk- my problem is not the logic - problem ist that the parallel connected Digital Outputs not work in the same way - I send true/false from the "And" node and only DOutBit_1 really switch, DOutBit_7 not, same with DOutBit_2 .... only at DOutBit_6 its working....

Hi Gunnar, From here I can unfortunately only try to help you with half knowledge. Can you try to implement this logic for example in Python? Maybe there are timing relevant things in Node-RED or other things that we can't understand. My idea is to just simplify your application.