Howto: PLC Reef Controller II

[javajaws]

Let me take a look at the specs of the units and see which one looks like your best bet, the issue that may arise is the lenght of code that can be programmed into the units. I complex setup code have an extremely long code length.

All the EZPLC units have 64KB total memory (which I believe is relatively a lot and more than a DL06). FYI, here is a link to the EZPLC online downloadable docs:

http://www.ezautomation.net/downloads/docs/docs.php

 

[gabe21804]

All the EZPLC units have 64KB total memory (which I believe is relatively a lot and more than a DL06). FYI, here is a link to the EZPLC online downloadable docs:

http://www.ezautomation.net/downloads/docs/docs.php

Yeah I noticed the memory thing when I looked at the features list.....

Wow looked over the programming manual, for the most part it looks like you could translate my code for the s7 line for line into this thing.

 

[javajaws]

OK, I did a price check for nearly identical EZPLC and DL06 setups (identical enough to meet our needs). Here first are the numbers:

EZPLC-D-48 (6 slot PLC base, AC power) 168
EZPLC-EDIT (Software) 49
EZPLC-BAT (Backup Battery) 20
EZP-PGMCBL (Programming Cable) 20
EZIO-8DCI (8 DC inputs) 19
EZIO-8DCI (8 DC inputs) 19
EZIO-8DCON (8 DC sinking outputs) 19
EZIO-8DCON (8 DC sinking outputs) 19
EZIO-8ANIC (8 ch 4-20 mA analog input) 99
EZIO-4THI (4 ch Thermocouple input) 139

Total: $571


D0-06DD1 (PLC) 199
PC-PGM_BRICK (Software) 149
D2-BAT-1 (Backup Battery) 12
D2-DSCBL (Programming Cable) 30
F0-04AD-1 (4 ch 4-20 mA analog input) 79
F0-04THM (4 ch Thermocouple input) 199

Total: $668


So for our configs...the only real significant savings with the EZPLC comes from the software cost and the cost of the thermocouple input. Given the relatively close cost (when all things are considered...counting probes, transmitters, wiring, etc.) I don't think I can personally rule out the DL06 based on price alone....$100 isn't a big deal to me.


A few comments:

Ethernet can be added at a later date to the DL06 ($175 option module). Ethernet for the EZPLC has to be ordered with the base ($99, can't add at a later date though).

The DL06 has a nifty 2-line LCD display available for $69 (mounts on the front of the PLC). It can display memory variables as well as text on each line (for displaying temp/ph/etc.). It also has some buttons for navigating and changing setpoints, etc. (I presume).

Both units can utilize external displays such as EzText.

With this configuration, the DL06 would have 2 option slots available for future expansion (1 if you add the Ethernet module). The EZPLC would be maxed out.

I'm not sure if the EZPLC supports PID loops...the DL06 includes support for 8.

The DL06 has a much larger instruction set compared to the EZPLC...could make programmability an issue. Probably not a big deal for our relatively simple needs though.

The DL06 has an RTD input module available, the EZPLC does not (as of yet).

The DL06 has a relatively large user base and help can easily be found from outside resources. The EZPLC is new and does not have a large user base as of yet.

AutomationDirect technical support is supposed to be pretty good, haven't heard anything about EZPLC yet.


So I'm personally leaning more to the proven product that has been around the block...the DL06. I just don't know if saving $100 is worth it in the long run to go with the EZPLC.

- Jason

 

[eleben]

JavaJaws I'm with you on this one. However, I think I will still tryout the EZPLC just so that we can get a comparison of everything. They do have a 30day return policy. I do like the overall quality of the AutomationDirect PLC (bias based on pictures only - not based on actual use). One of the only problems I have with the EZPLC is the fact that the ethernet has to be purchased now instead of it being an actual module. I do like the idea of remote monitoring and exporting it to computer using ethernet instead of the RS232 port.


One thing I do like about the EZPLC is the fact that the I/O are just modules that are removable and easily replaced with other (cheap $$$) modules if needed.

 

[inerratum]

I think is a good idea to try different plcs to see what we can do. Im having a rally hard time finding the siemens stuff that I need, cant even seem to find the programming cable for a reasonable price.

 

[javajaws]

I went ahead and bought the DL06 this morning. Got everything (including the LCD display) except the thermocouple unit...I'll add that later ($$).

BTW, 2 other things to consider:

The AC powered version of the DL06 has an auxilliary 24v power supply (300mA). This will help power some external relay circuits, a pH transmitter, etc.

The software for the DL06 seems more full featured than that of the EZPLC. I've downloaded demo versions of both and believe DirectSoft has way more features. Both pieces of software leave something to be desired in the usability department though (I'm a harsh critic though since I write developer tools for a living).

 

[eleben]

Did you get the D0-06AR, D0-06AA, or the DC version?

 

[javajaws]

D0-06DD1 (AC power DC in/out) - I plan on using it to power a relay bank. I didn't want to go with the internal relays because I wanted to use higher amp relays and thought I'd save the extra $30. I think I'll get something like the Ziplink 8-ch relay connector module (p/n ZL-CM08RL24) later for this.

 

[gabe21804]

Just a thought a 300ma 24v powersupply is extremely minimal. I bank of relays may come close to drawing 300ma's depending on what type they are and how many, relays do draw current, and no powersupply is 100% efficent.

In my situation I had to opt for a external 12vdc 2.5amp powersupply to run my fans, leds, and relays. I used one that has a 120 hardwired input instead of a plug in, I hate plug in transformers especially in a clean setup. In our world 24vdc wouln't run much other than a relay. On the other hand 12vdc can run cheap fans, you can run your float switch with 12vdc instead of 24vdc or 120vac, with a few resistors you can have a array of leds that simulates sunrise and sunset, and moonlight.

I'm extremely happy with my s7 setup, its not new but I think the total I'm at right now with everything electrical is $275.

 

[inerratum]

Hi gabe, I was wondering if you could take a close up pic of the analog and thermocouple module, preferably with the covers open. I want to try to draw up a diagram of all the wiring but I dont know what the inputs are on those 2 modules and how they need to be wired to transmitters etc.

Thanks, if its too much trouble please dont bother.

 

[eleben]

Eastn - I just wanted to give you a quick thanks for sending me the S7-200 CPU 224 Siemens PLC and the extra I/O module! It looks great - I just need to get the cable now.

 

[eleben]

Is the Siemens cable just a converter from RS485 to RS232 or is it more involved than that?

 

[eleben]

Never mind I answered my own question! Of course it isn't. I think I will be selling the Siemens PLC 224 and I/O module if I can't find the cable in a reasonable amount of time.

 

[gabe21804]

Hi gabe, I was wondering if you could take a close up pic of the analog and thermocouple module, preferably with the covers open. I want to try to draw up a diagram of all the wiring but I dont know what the inputs are on those 2 modules and how they need to be wired to transmitters etc.

Thanks, if its too much trouble please dont bother.

Ill post something later today.

 

[slug]

I've attepmted a couple different circuits to make high impedence signals readable by my automated system. I'm not an EE but I'm not entirely electronically challeng either and I can't get any of them to work. I can't see paying $250-300 for one of the transmitters listed here. The last circuit I tried was the one listed on barebottoms site with a max406 chip. Has anyone gotten this working?

I can turn relays on all day long but a system like this is a lot more usefull with inputs like ph/orp/conductivity. At least temp is easy.

 

[gabe21804]

I've attepmted a couple different circuits to make high impedence signals readable by my automated system. I'm not an EE but I'm not entirely electronically challeng either and I can't get any of them to work. I can't see paying $250-300 for one of the transmitters listed here. The last circuit I tried was the one listed on barebottoms site with a max406 chip. Has anyone gotten this working?

I can turn relays on all day long but a system like this is a lot more usefull with inputs like ph/orp/conductivity. At least temp is easy.

I've got a couple of circuits I'm going to try, before I make them I'm trying to grasp the full concept at every level of whats going on. I know basic electronics as far as what all the components do, but when I start sticking them together thats where I start to lose it, I just don't want to copy a schematic. I want to know and understand how it works before It gets built so I'm not wasting money when the the thing doesn't work.

On another note, that was one of the simpler ones I was going to try, I have a few others I found floating around google. One has builtin calibration and tempature compensation. I'm not really concerned about the tempature compensation because that can be done at the software level on the plc. The calibration is a must have, but this could also be done at the software level from what I've determined its just going to be some work.

This is by far the hardest component of this project, next to this is getting the communication link between the plc and the pc down.

 

[barebottoms]

The last circuit I tried was the one listed on barebottoms site with a max406 chip. Has anyone gotten this working?

Slug, what seems to be the problem with it? Are you getting a voltage out of the op-amp?

Honestly I've been way too busy with work to try it myself, but the good news is that if there is enough interest, one of the 1-Wire boards makers might make a driver for us. I've already sent him a pH probe to play with. Maybe if I can get a count of how many people are interested in how many drivers we can motivate him even more.

 

[slug]

Yeah I get a voltage out, but it doesn't change with ph. I'll recheck my layout and report more specifics. The +3v in lines get hot, kinda seems like something is shorted, but it's such a simple circuit kinda hard to screw up.

 

[gabe21804]

Here's the schematic I'm planning on using to build a prototype amplifier for a ph probe for the plc's a/i.

Full explanation is at the following site, this seems to be the perfect circuit for what were doing with the plc's. I think this is the most straightforward circuit I've seen, and its nice to have an explanation with something for once.

http://www.web-ee.com/Schematics/pH%20Meter/ph.htm

 

[gabe21804]

I got the lmc6001, lmc6041, and the lm4040DIZ-2.5 as samples from National, they were shipped overnight for free. I've always seen resistors that were labeled with there wattage levels and ohm values. What wattage level does this circuit require, also what style of resistor are we talking about?

Worst comes to worst, I've got almost nothing invested in this, the only thing I'll have to buy are the resistors; te opamps, and diode are samples. As for the probe, I'm thinking about using a pinpoint replacement probe, due to the fact there extremely cheap ($44).

If someone wants to help me out with the digikey part #'s for all the resistors and the tempature compensating resistors, I'd love the help its a pain to sit down and come up with all the part #'s in digikeys catalog.