Quote:
Originally Posted by Mr. E
Infuriating....
I also needed to wire a double solenoid valve and used the above suggestionis.
I can only move the piston out, however.
Can any body help?
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If you connected the SMC dual coils as Andy (and the IFI doc) suggested above (M+ to red of one coil, M- to red of second coil, and both blacks to ground), THEN it is most likely a switch wiring, or programming problem. (See below for more details.)
The SMC dual coil is a "spool valve". It works by shifting a shuttle back and forth, so
only one coil should be on at a time. Without vibration, it can "remember" the last state if both coils are off, but since the coils are rated for continuous energization, it's safer to simply keep one or the other on at any time. They only pull about an amp, so that's not too much drain.
HOWEVER, if both coils are turned on at the same time, the state is "indeterminant". It
probably will stay in the previous state, but that's not guaranteed if one coil is slightly stronger than the other.
In your case, I'm guessing one or more of the following things happened, as these are the most common mistakes:
1) The valves aren't wired as stated above.
2) Someone forgot to change one of the two 24VDC coils to 12VDC on the valve
3) You have a program bug (I'm assuming you're mapping a switch or two)
-a) Your switches are not wired to the OI correctly
-b) You're reading the wrong switch on the OI
-c) The logic of mapping the switch to relay outputs is incorrect
-d) The wrong relay port(s) were written (you should be talking to a FOWARD and a REVERSE on a SINGLE relay port)
-e) You didn't turn off one coil when you turned the other on.
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4) There's a power problem with the Spike (no power, breaker failure, miswired Spike power leads, etc..)
5) Defective Spike - one side is dead (it happens!)
6) Damaged wiring, breaking the circuit
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For wiring, the most common wiring is to use one button bit on the OI. Connect a SPST (single pole, single throw) switch from that bit to ground. The software then looks at the switch state, and on the SAME relay either:
A) turn FWD on and REV off
OR ELSE
B) turn REV on and FWD off
This technique will energize one and only one coil, and keep that one on to insure it
stays in that state until you select the other one.
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Another trick: Take a PWM cable, and make a "monitor block" in the middle. Separate the three wires in the middle of the cable from each other. Strip back a little insulation on each wire, enough to circle them around the screws on a three terminal barrier strip. This "extension cable" now allows you access to each of the three wires in a pwm cable for voltage testing, or an oscilloscope connection. This in turn allows you to quickly check both PWM/Victor signals, AND Spike relay signals to see if your problem is in the spike & valve (or Victor & Motor) hardware, or with OI switches & programming.
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I hope this helps you diagnose your problem. Please let us know what you found!
Note to other people --- The main difference in application between the single and the double coil valves are:
A) Single coil valves are normally used when you want the coil to SWITCH TO a SPECIFIC STATE when the power goes off.
B) Double coil valves are used when you want the coil to REMAIN in the LAST SET STATE when the power goes off.
Examples:
- Use a SINGLE coil valve on a pneumatic gripper's "pinch" axis, to
guarantee it OPENS at the end of the round, to potentially score that last point while you were busy focusing on positioning your robot
to score and forgot to open the gripper before that last panic second. (For this game, there
are ways to insure it still holds onto a Keeper while awaiting autonomous startup, but I'll leave that as an exercise for you...)
- Use a DOUBLE coil valve on a ramp deployment cylinder, so it starts in the retracted state, but then STAYS OUT and not tries to fold up again when the power ends.
I hope this answers most of your questions.
- Keith McClary
Chief Engineer, Team 1502 "Technical Difficulties"