PLC temperature inputs

[86turbodsl]

Aside from my other thread on PLC and hardware interfacing, does anyone have suggestions on cheap/er temperature inputs to a plc? Planning on Automation direct control of SSR/pumps/etc. As industrial controls go, PLCs are great and easy to program, but the inputs other than discrete signals can get harder to do cheaply. I have put together DL-06's in the past and used RTD modules, but they are more expensive than i really want on this job. Can there be usable temp inputs from the other side of things, like 1wire feeding the HMI computer and the HMI just putting values into the PLC over modbus? Is 1wire even fast enough to run an electric element PID loop?

RTD's or Thermocouples into a PLC is easy with just spending money, but I"m trying to keep the wife happy by making good beer consistently WITHOUT spending our kids' inheritance on the automation.

Discussion?

 

[muhteeus]

Aside from my other thread on PLC and hardware interfacing, does anyone have suggestions on cheap/er temperature inputs to a plc? Planning on Automation direct control of SSR/pumps/etc. As industrial controls go, PLCs are great and easy to program, but the inputs other than discrete signals can get harder to do cheaply. I have put together DL-06's in the past and used RTD modules, but they are more expensive than i really want on this job. Can there be usable temp inputs from the other side of things, like 1wire feeding the HMI computer and the HMI just putting values into the PLC over modbus? Is 1wire even fast enough to run an electric element PID loop?

RTD's or Thermocouples into a PLC is easy with just spending money, but I"m trying to keep the wife happy by making good beer consistently WITHOUT spending our kids' inheritance on the automation.

Discussion?

You could look at ways to make an arduino talk to the PLC through modbus/serial comms. Then you could take advantage of the I2C or other available protocols on the board. Someone in the Automated Brewing sub is working on something similar. You could extend this to multiple arduinos.

Edit: Not the one I saw but HERE is arduino doing RTD. Also HERE is arduino doing modbus!

 

[86turbodsl]

Ok, some research looks like arduino, raspberry pi, and similar controllers talking modbus might be a good way to go.

 

[Maxkling]

You can get a 4 channel analog input (4-20ma) for less than 100$ and use a signal conditioner or temperature transmitter.

How much you looking to spend?

 

[86turbodsl]

I'd like to avoid the expensive add in slot cards that only add 4 temps. I have a DL06 with 3 of them controlling my HVAC in my house, and even buying cards on ebay i have over 500 into just the plc. So i'd like to stay away from add in slot cards. spend the money on motorized ball valves and stainless. I figured if i can find an inexpensive way to add 1-wire or thermocouples using 3-rd party support, i can add more than 4 temps per slot. I'd also like to do more with hvac temp monitoring around the house, so it would be great to figure this out for other reasons.

 

[BigBlock]

I just got my Arduino communicating with my automation direct click plc ( mb rtu rs485) a couple nights ago. I'm sure the DL 06 will have no problem communicating as well. By coincidence I happen to have a DL 05 running my boiler.
I used the simple Modbus library that was linked above and got it working pretty easily after correcting for some dumb mistakes.if you're interested I can share my mechanical engineers version of Arduino code. but the best way is probably to start with the example in that library. I got into working with Arduinos after I bought my plc. If I were to do it all over again I'd be tempted just to use the Arduino, however I do like the ease of programming on the Click.
Right now I'm still planning to use the schneider electric igss HMI (free 50)software. that's what is running on my boiler setup right now to monitor and log data. It works decent and the price is right.

 

[86turbodsl]

M.E. huh? me too. I'm torn between the arduino or the rpi. I'll check into the HMI. I haven't purchased anything yet, i'm hoping to engineer the whole enchilada before i start buying/building. You know the old saying ... fail to plan, plan to fail.

 

[stinger84]

Never tried Arduino, instead I purchased a Pixsys temperature controller for brewery stuff, works pretty well.
My thought is that HMI is a very expensive solution, more suitable for industrial automation applications.