Relay basics

[BillB]

Mike, Your post provided the info I needed to get me over the hump. THANK YOU!!!! Much appreciated! Thank you for taking the time to provide that and all the other detailed notes. I am going to print your last post and keep it in my Acorn folder for all future assembly.

BUT something strange is going on with the button on VCP.
I turn OFF auto coolant mode and click the mist bottom, NOTHING! tried it dozens of times. The button will not come on, no LED on either I've rebooted as well. same thing.

I go into the I/O screen highlight my output (#2) and hit ctrl alt f to turn the output on. GOOD, it's green, and the solenoid comes on.

I then post a small facing operation file from Fusion with mist turned on. Post it to the control and machine and the M7 code is there but the solenoid does NOT come on? When running this file the LED on the mist button DOES come on.?

The solenoid valve is NC

Thoughts? Could the macro be corrupt? Something wrong with the button?

Report included

[Richards]

Congratulations on your progess.

Now to the Mist Button problem: Have you assigned the Mist Button to an Output in Wizard? When I have the Mist Button UNASSIGNED, it sometimes has a quick flash when I try to toggle it using VCP.

I turned on the I/O screen (Alt-I) so that I could watch the outputs. I turned on Mist by sending M7 via MDI. With the Mist Button set to Auto on the VCP, the MDI turned on the Mist's LED when I issued the M8 command. It turned off when I issued the M9 command.

Next step: I used Wizard to assign Mist to Output #2. I turned on I/O with Alt-I to watch Output #2. In Manual Mode, the Mist Button on the VCP toggles Output #2. In MDI, with the VCP set to Auto Mode, M7 turns on Output #2, M9 turns off Output #2.

NOTE: If Output #2 has been FORCED ON or OFF by selecting Output #2 with the cursor keys and then pressing Alt + Ctl + F, then neither the MDI commands (M7 and M9) nor the VCP Mist Button will have any effect on Output #2. There is a white line beneath the Output in the I/O screen when the output has been forced On or Off. Press Ctl + Alt + F until the underline is removed.

In the following screen shots, look carefully at Output #2.

.

off.JPG (9.47 KiB) Viewed 2342 times

FORCED Off
.

On.JPG (9.54 KiB) Viewed 2342 times

FORCED On
.

normal.JPG (9.35 KiB) Viewed 2342 times

Not Forced

[BillB]

My hats off to you sir. Thank you, got it, ; ) the white lines were on all on, on the outputs 2-7 because when I was testing I used alt-ctrl-f to toggle them all on and off.

What is the function of this mode with the white underline? Like a temporary way to disable the switch or output?

Tested with buttons, MDI, and posting file all good to go with the air on.

[BillB]

Hey Mike, Thank you again for all your help. One other thing I want to get running is a small AC fish pond pump. I'm not even sure it will hold up to any type of coolant mist OR soluble oil ? Working with DC is one thing and I'm totally convertible experimenting with that but when it comes to AC I'm honestly not convertible unless I have EXACT instructions on how to wire it up. What input can you offer when it comes to AC devices? I I don't want to fry myself or Acorn. Im not even sure it will be part of my final setup as Im not sure if I will run flood, mist or just air and add oil with brush.

[Richards]

Bill,
Those forced outputs have caught me too. I should know better. I use forced outputs on AutomationDirect and Allen Bradley PLCs (Programmable Logic Controllers) all the time. The purpose of "forced" I/O is to be able to test logic without needing to wire up the physical device. The Acorn has its own PLC built in. The "white underscore line" is a visual indication that the I/O line has been forced On or Off.

Connecting a low power AC device to the Acorn is similar to connecting a DC device. Refer back to the photo that showed how I connect an DC indicator lamp to the Acorn's relay outputs. In that photo, the Yellow wire is +24VDC from the power supply, the Blue wire was +24VDC from the relay's N/O terminal) to the (+) side of DC indicator lamp. The Black wire is GROUND or COMMON from the DC power supply. It was connected to the (-) side of the DC indicator lamp. If you control an AC device with the Acorn's relay board, replace the Yellow wire in my photo with a Black wire (North America standard). Connect one end of that wire to the relay's Common terminal. Connect the other end of that wire to AC Line (Hot or L1). Connect a wire from the relay's N/O terminal to the AC device (Blue wire in my photo. I suggest that you use Black wire to indicate AC Line voltage). Connect the other side of the AC device to AC Neutral (White wire in North America, Blue wire in other parts of the world).

When I cut off the plug on an AC device (like the pump that you're planning on using), Note the shape of the contact blades in an AC device's power plug. The wider blade is AC Neutral. The narrower blade is AC Line (Hot or L1). The round contact on the plug is Earth (ground). When you cut off the device's AC plug, note the colors of the conductors in the cord that go to the plug. Normally, Black or Brown is AC Line (Hot), White or Blue is AC Neutral, and Green or Green/Yellow is Earth. I'm overly cautious, but I always use a multimeter to verify that the plug was wired properly. Set the meter to resistance mode. A low or zero reading shows continuity between the wire and the plug's blade or pin. The high reading show non-continuity. To recap, connect a Black or Brown Line (Hot) wire from your fused AC source to the relay's Common terminal. Connect another wire from the relay's N/O terminal to the Line (Hot) side of the device you're controlling. Connect a White or Blue Neutral wire to AC Neutral. If the power cable has a Green or Green/Yellow wire, connect that wire to the Earth/Ground strap or screw on your metal enclosure.

I only use the Acorn's relay board to drive small loads. Normally I also attach a fuse that can handle the device's current load between the relay's Common terminal and the power source.

Keep in mind that 120VAC can be lethal. Look at how a light bulb socket is wired in your house. The Black wire goes to the base of the light's socket. That wire goes from the lamp's socket to the AC switch that turns the lamp On/Off. The White wire goes to the screw portion of the lamp's socket. That wire connects to the White neutral wire in the switch box that houses the On/Off switch for the lamp. The bare copper wire connects the metal base of the lamp's fixture to the ground/earth screw. That wire connects to the bare copper wire in the switch box. The thing to note, is that the screw base of the lamp that you can touch is connected to AC Neutral. The lamp's socket is constructed such that when you unscrew the bulb from the socket, the AC Line (Hot) connection is disconnected from the lamp before you can touch the screw portion of the lamp. If you wired the lamp backwards so that the AC Line (Hot) was wired to the lamp's screw and the white wire was wired to the lamp's base contact, the lamp would still work, but you could get a lethal shock when you replace the lamp. Use a little caution when you wire up anything. Protect yourself. If you're not absolutely sure about how to safely wire a device into your control box, have an electrician check things before you turn things on. I've been careless a few times and gotten a good shock. It's not pleasant and it can be lethal.

[Yelleke]

I only use the Acorn's relay board to drive small loads

is a 220volt 60watt submersible waterpump a high load ? (water cooling)
is a 220volt 6W waterproof LED-lamp a small load ? (work light)
and do I need a snubber for any of them ?

don't want to arc my acorn relay board

Yelleke

[cncsnw]

is a 220volt 60watt submersible waterpump a high load ? (water cooling)
is a 220volt 6W waterproof LED-lamp a small load ? (work light)
and do I need a snubber for any of them ?

Both are well within the rated current of the small relays.

However, I would run at least the pump motor via a separate DPDT relay anyway, for three reasons:
1) The motor is an inductive load, more prone to arcing when switched off. It may also draw excessive current if it is stalled.
2) Because of (1), you should put an RC or varistor snubber on it. That is easier to do if both leads are side-by-side on a relay socket.
3) Since 220VAC and 240VAC has two hot legs, if you only switch one, you always have a live wire out at the motor.

Number (3) applies equally to your light. While you can effectively switch a 220V or 240V single-phase load on and off by switching just one leg, I personally like to switch both legs, so that there is no live wire at the device when it is switched off.