I've checked connections for shorts, read about loads, try multiple power supplies and, stumped.
Have this 8 channel relay hooked up to an Arduino Uno.
Have it isolated with a 5V power supply (and have also just used the Arduino to power it)
WHEN I tie in the 12V 1A + to the relay, it will cycle once, maybe twice, then lock up the whole relay board.
I tried a diode think EMF but no luck, still locked it up.
It locks up the relay board AND the Arduino in the process
I see no shorts in any connections.
Where should I be looking, doing, thinking?
Thank you for any insight
TVMiller:
WHEN I tie in the 12V 1A + to the relay, it will cycle once, maybe twice, then lock up the whole relay board.
To where, exactly? To the screw terminals?
It locks up the relay board AND the Arduino in the process
Since it claims to have optocouplers, then a manufacturing defect would be the most likely suspect. You could test the board in isolation, separated from the Arduino (just using a jumper wire to apply +5VDC to the logic pins), using a multimeter to measure voltage various places (including your 5V power supplies) to see if 12V is leaking somewhere it shouldn't.
I used this same relay to operate 3 garage doors in a shop.. Open,stop,close for each door.. I had to add 1 more relay board to do them all.. I had the same problem, I isolated power and ground from different power supplies for the arduino and the relays but the problem persisted.. It only happened when I was switching a load with the relays.. I surmised that it was EMI so I moved the relays away from the arduino and lessened the severity but it still would lock up pretty regularly.. especially multiple relay operation in succession.. What finally fixed it for me was using a 'snubber' on each of the relays contacts.. Same idea as a diode but since mine was low voltage ac(25v) I couldn't use a diode.. Check out the link below and start doing some googling.. I have nothing to do with the link below, not advertising or suggesting you buy from that seller, just showing what I used.. I bought mine cheaper from someone else, this was just the first pic I found of what I used..
edited: I was just thinking/re reading your post.. your not supplying the relay winding's with 12 volts? Those are 5 volt relays.. They can switch higher but the winding's themselves shouldn't see more than 5 volts.
I was just thinking/re reading your post.. your not supplying the relay winding's with 12 volts? Those are 5 volt relays.. They can switch higher but the winding's themselves shouldn't see more than 5 volts.
12V is on the screws
5V on the relays (via Arduino OR to JDVCC), that's all kosher.
I isolated the relay from the Arduino and just ran a switch for the input and the isolated JDVCC from a 5V supply and when I connect the 12V+ to the screws, it locks up the entire board EVEN IF only one relay is hooked up.
Can EMI send voltage back through the other side of the relay which would cause this disruption?
Tek1299, I looked at such a suppressor but when I next get a chance, I am going to try a resistor/capacitor I read as an alternative to running a diode.
12V is on the screws
5V on the relays (via Arduino OR to JDVCC), that's all kosher.
I isolated the relay from the Arduino and just ran a switch for the input and the isolated JDVCC from a 5V supply and when I connect the 12V+ to the screws, it locks up the entire board EVEN IF only one relay is hooked up.
Its not clear what you are using the 12V for, or how its connected.
Can you provide a more detailed connection description, diagram or schematic?
Do the relays operate normally with the 12V disconnected?
Do you have separate power supplies ... one for the Arduino and one for the relay board?
Note: The 5V power from the Arduino would not be enough to power this board (especially when the relay(s) are turned on).
Relay Contact Description:
J6-1 is NO (normally open)
J6-2 is COM (common)
J6-3 is NC (normally closed)
EDIT: OK, I see from a previous reply that it only happens when switching a load, so it looks like it could be EMI, or perhaps you don't have the grounds isolated - the relay board ground or 12V ground should not be connected to the Arduino ground.
To answer your question, no, there shouldn't be anything reflected back to the Arduino from the switching contact side of the relays. Isolation is one of the things that relays provide.
I would disconnect the relay module, everything removed down to the bare board.
Once all you have is the board and an ohmmeter, I would attach one probe to VCC then probe each of the 24 screws on the relay contact side of the board. Repeat the test, moving the stationary probe to JD-VCC and again check each of the 24 screws. You should measure infinite resistance with all 48 measurements. If there is resistance of any measurable level, there's your fault.
It could be either a shorted PC trace, or a bad relay.
Also don't forget RFI ... I've seen electronic issues even when adequate EMI / snubber protection is used. Especially if relays are being switched in close proximity to the electronics. The problem becomes exponentially worse with higher switched voltages.
RFI Solution: Increase the distance of the switched load(s) from the electronics (Arduino) or use an RFI shielded case for protection.
I don't think the distinction between "RFI" and "EMI" is valid - you are merely talking about the rapidity of the transients.
What is important is to consider the magnetic component, not just separating the circuits, but ensuring all load, power and particularly signal pairs run together so that no loops are formed.
I don't think the distinction between "RFI" and "EMI" is valid - you are merely talking about the rapidity of the transients.
Correct. I really shouldn't have separated the terms because they're commonly used to mean the same thing. The point I was trying to make is how operating relays close to electronics can cause havoc, even though there's optical isolation or no electrical connection or relationship between the circuits whatsoever. How one electrical circuit can pickup transients from another electrical circuit through the airwaves. I've seen MPUs hang, counters jump, displays freeze, etc. due to its close proximity to switching relays, transformers, solenoids.
This is stupid, but here we go.
I had the Commons screws connected in series so each relay NO could access the 12V+.
Taking EMI in to consideration, I switched the 12V+ from the Common to the NO thinking that small sliver of wire in side with the constant 12V+ via common was producing just enough EMI to back up. I know, sounds knuckle headed but, it worked.
The 12V+ is on the NO screws and the solenoids the 12V goes to is on the Common.
Sigh.