Solenoid LEDs not turning on

FIRST General Forum
1

The Solenoid Leds are not turning on. What is the problem?

2

What solenoids are you using? How are you powering them? How are you sending them a signal? I’d love to help you, but I need some information.

If you’d rather not share for whatever reason, feel free to drop me a PM.

3

The PCM solenoid indicator lights will not turn on without:

  • Power from the PDP (look for a blinking status light on the PCM)

  • CAN communication from the roboRIO (look for a blinking green PCM status light)

  • Running code on the roboRIO

  • Driver Station connected and Enabled

  • Code instantiated or Open’d solenoid

  • Code ordering a solenoid ON or Forward/Reverse
    The indicator lights on the solenoid itself and for the solenoid to actually work requires:

  • The PCM jumper for 12v vs 24v must match the rating on the solenoid coil.

  • The solenoid must be connected to the PCM solenoid outputs

  • The PCM solenoid indicator lights must be lit (see above)

  • The solenoid must be receiving pressure of at least 20-30psi.
    *]The mechanical releases on the solenoid itself must release pressure when pushed

4

Depending on the brand, the lights on most solenoids will work, even when the last two criteria aren’t met. The coil will energize, but nothing will move.

5

Yea, I wandered off into general solenoid troubleshooting :slight_smile:

6

If you have the solenoid turning on through button presses when you enable and press them do the lights turn on because depending on the code when enabling the robot it doesn’t mean the solenoid lights will turn on. (For example if x button pressed solenoid forward y button pressed solenoid reverse) Just try enabling and pressing the buttons.

7

Additional item: (Might be an issue with some solenoids?) Polarity; depending on the snubber circuit used (and what exact circuit was used for the light) DC polarity can matter.

With most off the shelf DC relays this does matter since they use diode snubbers, which short out if you get the polarity wrong. If the relay/solenoid (such as the omron relays I see at work) has a single LED for the indicator light (w/o a bridge rectifier), they will be polarized in respect to the indicator light.

Resititive snubbers and dual LED relays/solenoids (such as the SMC solenoids I encounter at work) are dual polarity. Check the datasheet if you’re unsure, or just flip the wires and see if it helps.