Help on programmable power relay timer(??)

I'm not sure if this is what these forums are for and I'm pretty sure my title makes me a moron but... I'm looking for some help figuring out how to power these parts for a programmed interval:

https://www.amazon.com/Aquatec-8800-Booster-Pump-Transformer/dp/B003ZJMSEY

https://www.freshwatersystems.com/p...ff-solenoid-valve-with-qc-fittings-24vac.aspx

The idea is that the pump will turn on for a programmed time. Then, one after the other, each solenoid opens for a fraction of that time; with a bit of overlapping. Afterwards, everything is off for a set time.

I'm clueless what part(s) to look for and figured you all could point me in the right direction. I could conceivably have 200 solenoids per pump. So I'd like any thoughts on handling future expansions. I'd also be thrilled if this could be networked to remove the display and controls cost.

Thanks ahead for any thoughts!

You looking to build or buy? If building, what are your skills?

Is the time duration for each solenoid valve the same, or are they all different?

The idea is that the pump will turn on for a programmed time. Then, one after the other, each solenoid opens for a fraction of that time; with a bit of overlapping.

Click to expand...

Are you talking milliseconds, seconds, minutes,.....?

I'm not necessarily suggesting this: https://www.tri-plc.com/e10intro.htm#e10rly but rather give you an idea of what's possible. The program space doesn't look like it could handle 200 solenoids.

Again, just doing some searching, I found this: **broken link removed** They provide lots of I/O's but can't directly operate valves.

MODBUS is an interesting networking standard. One version runs over Ethernet. RS485 is a multi-drop serial standard.

Here is another interesting product: https://www.automationdirect.com/ad...inator_I-z-O_Discrete_Output_Modules/T1K-08TA but you need a power supply module and a networking module and, of course, a 24 VAC power supply for your valve. MODBUS and Ethernet are available options.

Key terms are MODBUS, networking, I/O modules, PLC, DIN rail, DIN terminals, RS485

When you mention 200 solenoids per pump, what kind of distances between the valves. i.e. Does it make sense to "distribute" the I/O over say 10 locations?

Remember, I'm not advocating anything. Just trying to get your feet wet.

MikeMl said:

You looking to build or buy? If building, what are your skills?

Is the time duration for each solenoid valve the same, or are they all different?

Click to expand...

I'd love to just buy something but I've been looking around and have yet to find anything close. Skills are in 10 years of websites and I put together my comps from newegg... lol. So compared to you guys, probably not much. I can make jello

alec_t said:

Are you talking milliseconds, seconds, minutes,.....?

Click to expand...

The pump would turn on and each solenoid would open for 5-6 seconds, depending on what overlap I'd need to not burn out the pump. After each had opened the pump would turn off for 20 minutes and the process would repeat. [edit: scratch the first part. The pump wouldn't turn on until after the first solenoid was open]

I guess I could mention that this is for an aeroponics system and for unifying multiple systems under a single pump, filter and reservoir as well as eliminating the need for an accumulator tank and high pressure solenoids -- potentially saving $1,500 per system.

KeepItSimpleStupid said:

When you mention 200 solenoids per pump, what kind of distances between the valves. i.e. Does it make sense to "distribute" the I/O over say 10 locations?

Click to expand...

I would try to keep them as close together as possible. There would be one main line of 1/4" Tees, each connected to a solenoid [edit: leading to an aero system]

I'll have to take a minute to acclimate my feet to these waters.

Somethink like:
t=0; all valves off
t=1 ; valve 1 on
t= 2; valve 1 on
t=3; valve 1 on
t=4; valve 1 on
t-5; valve 1 on; valve 2 on
t=6 valve 1 off; valve 2 on

So, if the interval were seconds. Each valve would stay on for say 5 sec, and the next valve would turn on at the 5 second mark so at one point in time, you would have two valves on and then onto the next one?

Would those times be totally fixed. i.e. would
Time on and (sequential 2-valve dwell time) define the system?

e.g.
all valves off V(*) = 0
for v=1 to 199 (# of valves -1)
V(v) =1; on
wait ( 4 sec)
V(v+1) =1; on
wait (1 sec)
V(v) =0; off
Next v

I didn't deal with the repeat, nor the 200 valve being of while the 1st one being on which i would assume that you would want. Basically a ring counter.

That could make the programming simple.

Thinking out loud:

If only two valves can be on at one time, you might consider two matrixes. Say a 14 x 14 matrix which is 196 valves, one on at a time and another matrix for the other valve. I'm not sure it's possible though. It MIGHT be possible to turn on 196 valves, 2 at a time with 56 I/O points. I need to think about it.

But again, you may have to employ solid state switching because of the number of activations/year. I'm also not sure you can save $1500 either.

If your going to make bunches of these things, then it may be possible to do it in an entirely different way.

So, far the code seems minimal. The hardest part is getting the amount of digital outputs. If this thin is operating 24/7/365 then relays are out the door/window. If you need a user interface that adds complexity. If you can hard code the delays, that makes it easy. A test mode also adds complexity. e.g. Turn on valve 180 indefinately. Then possibly a double display for which valves are on.


Can the valves be purchased with a DC coil voltage such as 24 VDC?

For giggles, when you try to get intimate with a small micocontroller and want 200 ports, even that gets tough. This device, https://www.gravitech.us/i2c16gpex.html would allow 128 I/O pins on a I2C bus. I2C is Inner IC communications and it's standard on many microcontrollers. Its my understanding that you could multiplex the bus, so you could conceivably increase the pin count.

Each relay, if we go one at a time, might need a triac for AC and an adequate heatsink or one or two big ones. It would need a snubber and drivers for each as well. Even 200 * $3.00/channel is $600 and I'm not saying a channel would cost $3. You may need a LED indicator as well.

What, exactly, is an aeroponics system?

Meanwhile, go get your feet wet.

Yea the programming side should be rather simple. The component side is where i fall flat on my face.

The $1,500ish savings was per setup/section. Well, per every 2 sections. If I were to do the full 200 then it would save roughly $150,000ish. Though, I would only be starting with under ten sections. So the $600 wouldn't be bad.

Aeroponics is where you grow plants not in a growing medium (dirt) but suspended in air and intermittently sprayed with a nutrient rich water. Uses 2-5% of the water used by traditional farming, no pesticides, fertilizer, herbicides just to name a few benefits.

**broken link removed**
[each solenoid would lead to one of the black trays]

OK, Hydroponics without the dirt. I get it.

Why does this remind me of the movie COMA? https://en.wikipedia.org/wiki/Coma_(1978_film)

So, you could say do say 16 valves per controller, if the cost was right?

Here is yet adding to the other ideas is another micro PLC; https://www.omron247.com/Industrial...chType=category&dispProdList=Y&dispProdDocs=Y

These I/O modules https://www.power-io.com/products/oac.htm or AC output modules have been the traditional way of interfacing. They can interface 5V logic to your AC valves, but they are like $30 per point or per valve. But these give you small size, DIN rail mountable, opto isolation, fuse, LED indicators etc.

A Logic supply is required (4 to 24 V) and then what's called open collector outputs drive these devices.
Open collector outputs are common. This https://www.electro-tech-online.com/custompdfs/2012/11/uln2003a.pdf is an IC which can convert TTL outputs to Open collector outputs. There are 7 channels to a chip. There is an 8 channel version and I think a 3.3 V logic version.

In the industrial world, control cabinets such as NEMA 1 rated with a removeable back panel. Usually you mount DIN rail to that 1/8" alluminum with tapped holes. Wiring duct is added to provide a raceway within the cabinet to run wires.

DIN terminal blocks such as these https://www.altechcorp.com/HTML/DIN_Rail_Blocks-A.html act like an erector set and are reuseable. Many times it's best to use terminal blocks for inputs and outputs and wire internally to the terminal blocks. i.e. Your solenoids could be attached to a double block where say the bottom level has a bus bar installed for say +24 VAC. You would use cord grips for your wires and attach to them to the double blocks.

This can lead down a path where you design and build your own Printed circuit board for say 16 valves.
What that can do is reduce the cost.

Internally, you would wire the I/O modules to the block and the PLC to the I/O modules. HMI modules or even a PC can be used to set values within the PLC.

You need to find some balance.

I can also see that you might want to have a backup power source for your system. Some generators are not UPS (Uninteruptable Power Supply) compatible and this isn't too well known to novices.

If your good at programming in C, then this might do the trick: https://cubloc.com/product/08_01.php

although the features may be too restrictive.

It looks as if it could do 48 outputs, have an encoder and an LCD module, but it has trouble with multiple communication channels. An encoder is a user input knob that generally develops about 16 pulses per turn and can be illuminated with a bicolor LED (3 colors) and also contains a switch.

Interrupts don't seem possible either.

FRAM is a rather new technology that is non-volotile, and doesn't have any write limitations.