RevPi DIO Output LED Remains Red

[WillPi]

I am trying to create a circuit with a RevPi Connect 5 and a MIO and DIO modules. The MIO module works perfectly fine, but the DIO module's Output LED remains red no matter what I do. I have connected 24V PSU supply to the Input and Output pins on the top of the DIO module, and have a 24V supply to the bottom pins to power the DIO device. The RevPi can see the module and can read digital inputs from the input pins, but it cannot output anything from the digital output pins.

[Amar]

Hi Will,
Please work through the following steps in order:

1. Power cycle the DIO and reset piControl
First, switch off the 24V PSU feeding the DIO's X2 and X4 connectors completely — do not just do a software reset. Wait at least 10 seconds, then power back up. This procedure clears any latched fault state in the DIO's output IC that a software reset alone won't clear.

Give the Connect 5 a full 60-80 seconds to boot and for piControl to initialise. The DIO Power LED will flash red during init — this is normal.
Then reset the piControl driver:
piTest -x

Watch the DIO LEDs immediately as the driver resets — Power, IN and OUT should all come up green if everything is healthy.

2. If that doesn't fix it — stop CODESYS completely
sudo systemctl stop codesyscontrol
sudo systemctl status codesyscontrol

Should show inactive (dead). Then reset piControl again:
piTest -x

3. Build a clean minimal PiCtory config with the DIO only
Open PiCtory in your browser through the cockpit interface
https://<your-revpi-ip>/cockpit-revpi

In PiCtory, remove all other modules and configure only (The existing congfig.rsc would be overwritten by piCtory):
- RevPi Connect 5 (base module)
- RevPi DIO (one side only to start)

Leave any other expansion modules (e.g. MIO) out of the config for now — isolate the DIO test completely.
Hit File → Save as Start Config, then run:
piTest -x

4. Test the DIO on the left side of the Connect 5
Place the DIO on the left side in PiCtory, save as start config, run `piTest -x` and check:
piTest -d
piTest -r Output_Status_1
piTest -r Status_1

If the OUT LED goes green, test an output directly:
piTest -w O_1,1
piTest -r O_1
piTest -w O_1,0

5. If the left side fails, try the right side

The Connect 5 supports expansion modules on both sides. Power down completely, move the DIO module and PiBridge plug physically to the right side, update the position in PiCtory to match, save as start config, power back up and repeat the same checks.

What each outcome tells you
- OUT LED goes green after power cycle + `piTest -x` → latched fault state, now cleared
- Works after stopping CODESYS → the CODESYS application was holding outputs in a safe/reset state
- Works on one side only → PiBridge connector issue on the failing side
- Works on neither side without CODESYS → X2 output supply wiring issue or hardware fault on the DIO module
- Works on neither side regardless → likely a faulty DIO module

Please share the full output of each step to narrow it down further and also send an SOS report if the issue is not resolved.
Regards, Amar

[RamiGspo]

The red Output LED on the DIO module typically indicates that the 24V output power supply is either missing or not connected correctly. The DIO has separate power supply inputs for the input side and the output side. Both need their own 24V feed.

A quick way to verify using a single PSU is to bridge both the 24V and GND terminals from the input side to the output side. If the Output LED turns green after doing that, it confirms the output side was simply not receiving power.

Could you also double-check the polarity of the wiring on the output power terminals? If 24V and GND were accidentally swapped on the output side, the module may have been damaged. In that case, the LED would remain red even after correcting the wiring...

[WillPi]

Hi Amar,

Thank you for getting back so quickly, sorry I've taken so long to check this.

Step 1:
The piTest -x doesn't change the status of the Out LED on the DIO module.

Step 2:
Stopping codesys and then running piTest -x has the same result as step 1.

Step 3:
Creating a fresh config with only the revpiConnect 5 and the DIO also doesn't solve the LED issue.

Step 4:
piTest -d replies with:
Found 2 devices:

Address: 0 module type: 138 (0x8a) RevPi Connect 5 V1.0
Module is present
input offset: 0 length: 6
output offset: 6 length: 7

Address: 32 module type: 96 (0x60) RevPi DIO V1.5
Module is present
input offset: 13 length: 70
output offset: 83 length: 18

piTest -r Output_Status_1 and Status_1 both reply with:
Cannot find variable

Step 5:
Switching the DIO module from the left side to the right side results in the exact same outcomes for every step.

[WillPi]

Hi RamiGspo,

The polarity of the wires is correct and I have bridged between the two and used the same wires that power the Input side, where if I disconnect those wires the Input LED turns Red as well so I know those cables work, but when they are connected to the Output power terminals the Output LED remains red.