Programmable Logic Controllers (PLC) anyone?

[janson]

I have recently embarked on automating my tank with a PLC. Anyone else in to this? I am currently using an Allen Bradley 1000 MicroLogix controller. I have plently of I/O's to expand what I actually control. At the time of this writing, I am only controlling my lights and an automatic top off. Would like to hear of other ideas/ladder logic that anybody has or is trying!

janson

 

[janson]

Here are the rungs that I am currently using. I implemented this in part because I was adding more lights to my tank and wanted a way to easily "adjust" the light cycle of the new lights so as to not shock the inhabitants. You will see in one rung where this takes place. I will slowly increase this timer to match T4:5 which then I could get rid of that rung altogether and modify T4:5 to control both sets of lights.

 

[janson]

oh, I am also going to control my power heads to create the wave motion I see a lot of people trying to get. This can be done with one relay and maybe two timers in two rungs. I'll post when it is done!

 

[driftin]

There's quite a few threads you might be interested in this DIY subforum
http://reefcentral.com/forums/forumdisplay.php?f=145

 

[janson]

Thanks....looking now!

 

[Lutefisk]

I've used an Allen Bradley SLC for somethings in the past. Obviously, PLC's work great for this stuff. Dedicated aquarium controllers tend to work out to be a better value, however.

 

[janson]

I would definately agree with you on the value portion. PLC's are expensive (so are the alternatives), however, doing this with a PLC, to me, seems like the better way as it can be modified infinately. I don't know because I have never owned a dedicated controller, but it seems to me that what you buy is what you are stuck with? Is that a fair statement? Whereas with the PLC the only limit is the wallet!

Plus, automation is my study and I love playing with them and making them do "stuff"! I had not been to RC lately, and wanted to see what I could find in this area! Thanks for your input.

 

[Lutefisk]

janson,

I've got a lot of experience on AB PLC5's as well as some GE with industrial systems that involved up to 9 separate PLC's communicate with each other and over 600 I/O points as well as multiple servo axises. These aren't the little mini and micro versions that are commonly available at a reasonable price now. So, I've been there and done that. Here is a QUICK summary of my thoughts.

Pluses for dedicated aquarium controllers:

• Analog inputs from temp, pH, ORP, ect. probes are very effectively handled compared to PLC with built in calibration routines, native units, etc.
• Built in user interface and data logging - something that takes a lot more work or money with industrial PLC's
• Other than plugging in power cords there really isn't any wiring required
• Many have analog outputs that are usable for controlling lights, wave makers, etc. (usually requires a separate output module or card on PLC)

Pluses for PLC's:

• You don't know how often I've wished I could program my AquaController with ladder-logic
• Ability to perform math operations
• Ability to time events
• PID control - would be nice for heaters (I have a separate temp controller that I've used for this ) Once you get it tuned it is very stable.

I'm out of time and need to run.

The punchline is that for common aquarium control tasks off the shelf controllers do a good job. I've also got a Neptune APEX that I'm messing with right now and its I/O is very expandable (with more modules coming that just plug into their propriety bus).


Paul