PLC users

[Hydropimp]

I want to use a plc to operate a diy

ebb and grow controller with a digital timer

turn on my 600hps

Monitor ph and ec for rez

Needs some help putting it together I have electrical knowledge.

Just need to know what voltage plc to grab. I know it depends on the devices and sensors I am running. I think I will need a 120/240v.

Can I add a power supply to run 12v or 24v devices?

 

[slackx]

Asking the manufacturer is going to be best bet. Depending on what plc your using it may need an exspensive external attachment to service it. I've installed 2 plc's for 2 completely different tasks and they're pretty much a cake walk.

It all depends on scale...if your thinking plc im thinking you should probably go 240 just to ease up amperage. Your plc should already have power supplies to control some of those devices most are extremely expandable. Your devices should have there own power sources though making the PLC more of a relay than PSU.

 

[Hydropimp]

Thanks for the reply

I don't have the plc yet and I do want to use it as a rely.

Just need someone to guide me through it.

 

[rives]

From what I have seen, the fixed I/O micro plc's that run on ac do not have analog inputs, which is what you are going to need for pH, ec, temperature, etc. The amount of current being pulled by the plc isn't really a factor - they only use a few watts. Your best bet is going to be a 12vdc or 24vdc controller (check your sensors and see which voltage has better parts availability for what you want, and get the same voltage controller - you can then use one power supply for the controller and the sensors) with as many analog inputs as you can get, and then use some solid state relays to interface to your 120vac stuff. Opto 22, Potter & Brumfield, etc all make clean little boards that will accept 4,8,16,or 32 modules and can be configured for either/or input or output. Ebay frequently has good prices on these components.

 

[Hydropimp]

Rives and slackx

Thanks for the time.

I have seen a siemens logo plc that does 12/24 v dc which 4 can be used as analog 0-10v. I will buy the plc usb cord and the program.

I have a digital timer and a big relay to flip lights in for a flip flop.

I was looking through uncle Freedoms thread but no one is posting new info.

I need some one to walk me through this in purchasing sensors and equipment.

 

[rives]

You won't need the digital timer. You can program far more accurate and versatile timers in the plc, and have a number of programs set up for various things (veg, flower, whatever) and select between them. I haven't run across much information for stand-alone sensors for ec or pH that are meant to be integrated into a platform like this. I'm not saying that they don't exist, but a quick search didn't turn up anything promising. Omega Engineering has some stuff, but it is pretty spendy for experimenting with ($160-180 for one pH sensor). My experience with pH metering is that there must be a fair bit of magic going on because the damn things are sure temperamental. You might be better off going with dedicated controllers from people that make specialties out of this type of thing (BlueLab Dosetronic, for instance) and then integrating them with your plc. You would then use the plc for your timing functions, driving your lighting flip-flop, pump sequencing for the ebb&grow controller, fans, temperature, interlocks, etc.

 

[Hydropimp]

Well if I don't need the timer I will return it.

And as far as ph probes go for I can just buy a ph, ppm and temp meter for that much.

So how can I incorporate the plc with my diy ebb and grow controll bucket? Still need to make it.

And make a flip flop for one light

 

[rives]

So how can I incorporate the plc with my diy ebb and grow controll bucket? Still need to make it.

And make a flip flop for one light

The float switches on the control bucket will need to connect to plc inputs, and outputs would drive appropriate relays for the loads. The outputs on these little controllers are arguably their weakest link. They usually aren't serviceable if you blow one, and sometimes the fuse protection is for groups of outputs rather than individual ones. Using these outputs to drive a relay that is selected based on the load that it powers rather than trying to drive the load directly will make them last much longer. The relays need to be selected based on the voltage and current of the connected load, so the specifications would be much different for your pumps and for the flip-flop. As far as the voltage of the plc, select for whatever voltage gives you the versatility that you want (the ac models usually don't have analog I/O, but most of them have an internal power supply whereas the dc models usually take an external power supply) and for the voltage that you have most of - if you have 24vdc pumps and already have a 24vdc power supply, it wouldn't make much sense to have a 12vdc plc.