What we would ask is:
"Which of the suggestions submitted has addressed your issue ?"
"Have you tried any of the submitted suggestions ?"
"Have any of the suggestions "Worked" ?
here we go, updated my previous post to comply. see bold text:
Hi, It would be best to have a separate 5V "wall wart" or whatever to run the relay board itself.
I added separate power supply..
OK, done, improvement noted. it actually runs now, but still has drop-outs.
for the Arduino Mega PSU - should i use a >5V supply?
the one i now am using is a 2A one, but could i use a 9V 2A one? it has to supply the Mega, 1 x W5100 Ethernet board and 5 x DHT22 sensors.
i have not added any electrolytic capacitors, but i have a 1000uF 25V one i can add at the Arduino? i also have some 0.1uF ceramic capacitors - could i add these in various places - like on the W5100 board power lines?
Review how to actually isolate things HERE: and see the section on "Optical Isolation"..
yes, that site was VERY useful.
the suggestion to read that webpage helped.
based on that information I disconnected the 5V lines between my Arduino and the relay boards, removed the Vcc-JDVcc jumper and ran 5V lines from my Arduino to the Vcc connection next to the In1 & In2 of the relay boards, but no ground from the Arduino to the relay boards.
my 6 relays are all opto-isolated now.
Also review "Grounding".. You should have a "common ground point" which is then connected to the building ground. This typically would be the negative terminal on your main power supply and the Arduino ground and all the other device grounds would run separately to that common point.
I don't know if this helped.
as I already had a star grounding layout to my main 5V PSU. I DID have the Arduino connected to this GND, but disconnected it as in Terry's page it said:
The ONLY connection to Arduino would be
•Relay board VCC to Arduino +5V
•(signal pins to In0, IN1 etc)
yes, i have 'star' grounding, for my relay boards but i don't have the Arduino back to the star (yet - but I am considering trying this as well),
should i add that to the star and also add the W5100 back to the star (not the Arduino)
and should i ground the 5 x DHT22 sensors at the star too (not the Arduino)?
i am yet to add my mains wiring, but should i add the earth pin to the star too?
would an EMI filter be necessary (the 240VAC is for the inline 90W fan)
Also check: is it better with USB Disconnected from your programming computer? That's another path for Electromotive Interference.
this did not help.
yeah, USB not issue, only started with the 24VAC motor dampers (these i have noticed have relays inside that click when the damper reaches full open and full close)
Let us know what helps...
all of you typed out words are helping immensely!
also should the ICSP wires between the Mega and the W5100 Ethernet board be 'twisted' too? i didn't think so - but wondering?