Intro and questions

[ForumGroupy]

Hello,
To start, this is a very interesting system!!
Now, let me introduce myself. Long time freshwater tank keeper/Sunday afternoon tinkerer. Been using my Digital A'quit'us controllers till they couldn't the job anymore (they had a good run). Been reading and researching the Apeck$ system but am holding back on forking over 2.5k. Now I am here, so well met to all, especially Rob!

I've been reading, trying to get to know this system (options, quantities, lengths, limitations, etc.).

I got three questions that I haven't found definitive answers to.

1. What are the length limitations on the DB9 and ethernet cables? What lengths have been confirmed functional?

2. Does every pin on an extension module need to be connected? I assume not. I ask this not to waste some GPIOs. Example, I take a 6sensor/2DC extension, wire the ground, 4 sensors and the DC control pins to this first extension, then splice the gound and the other 2 sensor pins to another extension (which would be 40 feet of wire away). Of course both would have their own power supply. How about splitting a DB9 on 2 power bar extensions?

3. About the 15 meter DS18B20 on sale on the Robo-Tank website, is using this better than sending an extension with sensor input 14m away with a 1m DS18B20? Does one way deal better with interference and any other possible distance related problem?

These 3 questions are all related to having part of the Robo-Tank system 35 to 50 feet (as a wire is routed in my basement ceiling with house mains in the way) away from the controller board. Minimally I would like temp and outlets. Maybe I can get away with sending DC signals down to SSRs instead of outlets but temp is a must. Sensor inputs would be a really nice to have. Anyway.

Now to try to understand the programming philosophy. Saw a red flags or two about ATOs and AWCs that I need to read up on.


Thanks Rob and JFReyes for putting this on my radar! Very interesting work!

Later,
Groupy

[Rob F]

Hi Groupy, welcome to the forum.

Those are good questions and haven't been covered much, if at all. In the past I've done some tests but never to the max as I didn't have enough cables. The longest I've tested is 50 feet but it's been a while. I have lots of serial cables so I will do some tests tonight so I can get some fresh numbers and see if I can max out.

You're correct, you don't need to use every pin for an extension, I don't see any issue with your example as long as max cable length is ok. If you used a DB9 splitter you could simply cut a trace on the extension PCB so the signal pushes on to the next extension. If the splitter was on a DC port no trace should need to be cut as the DC port from each extension sharing the same pin would be mirrored. If the shared port is for a sensor you would need to cut the incoming trace or splice the cable.

For extending DS18B20's the end result would be the same no matter how you cut it. With a single DS18B20 on a pin you should be able to achieve up to 100 feet from the Pi without issue, ethernet cable is good to extend them. At this time I only have one 15m sensor. The two temp ports on controller are connected to separate Pi pin and you can also use any of the 6 sensor ports for more, each would be using it's own GPIO as well. Like this there is no star cable configuration and sensors can't interfere with each other.

I think 50 feet for everything will be ok, I will verify, but if the cable is running next to AC mains it could be an issue for temp sensors more than anything.

As we are talking cable lengths one that is extremely limited is the I2C bus. If you needed more DB9's for extensions and power bars you would need a PCA9685 expansion but this can only have 1 foot cable between it and controller. From it you would need to run long DB9's. Same with pH, if you wanted a 2nd you would need to extend the BNC cable on probe vs the cable that connects the circuit to controller.

What red flags did you spot for ATO and AWC?

[ForumGroupy]

Thanks Rob, for the welcome and for taking the time. Appreciated.
No worries for the red flags, my choice of words wasn't that good. My setup is a little different from average with my water change setup and ATO. It's just me wondering if I can do what I want. Not too long ago you wrote in an automatic water change post about upcoming features with rules, schedules and custom modes. There was also a thread that talked about momentary switches. These posts sent up a flag in my notes telling me I need to find more info on these topics.
So far, I've just looked into the hardware, not the software side of things. Now that I know what I have to play with, I need to find out how I can play with it all. That brings me to my next step, looking into the UI, system programming options, general philosophy of how thigs where built etc.

I really appreciate you testing out the wire lengths. Thanks. Just dont spend too much time on this, lol, your time is better used making this system grow!

Groupy

[Rob F]

Ah yes I see, if you have a Raspberry Pi you can load reef-pi and get a bit of a feel for it. You mentioned rules and custom modes which makes me think you're talking about my app, at this point you shouldn't base your purchase on it as there's still lots to do and I don't want people expecting it to be done by certain time frames as I'm not very good with those. It will be done at some point but for now you should use reef-pi or least plan based on what it can do. If you have any questions related I can try and clear things up.

Testing cable length limits is something I need to know, it's not good if I can't clearly answer a basic question like that. :) Thought I might get through it tonight but want to check everything so will post details tomorrow.

[Rob F]

Ran out of cable again. :) Thought the serial cables I have were 10 feet but only 6 so I got up to 90 feet without any hint of issue and that's with 15 connections. Voltage was still 3.3v at the power bar so it's likely 200-300 feet is ok. Same with the sensors, they are no problem either however the sensor module is powered through the cable so it probably wouldn't get to crazy lengths depending how many sensors it's powering up. For now I'm going to rate DB9 and Ethernet cable to 100 feet.

[ForumGroupy]

Thank-you Rob, that is great info. Should be plenty enough for my setup.
Yes, one of the post had to do with your app and I appreciated the honesty! My thoughts after reading that post was that reef-pi might be missing some possibilities and that you are working on adding some of those.
I will indeed do as you suggested and play with reef-pi. I had already understood that would be the only way to really confirm anything without becoming the number 2 poster here.
Thanks.
Groupy

[Rob F]

No problem and yeah I think that was about the momentary switch, reef-pi is always trying to do something based on the sensor instead of just listening for an on pulse. My app is the same at this point but I'll be adding a setting so the system knows it's a momentary switch.

[ForumGroupy]

Being able to deal with momentary switches would be a great feature. Technically not needed but boy would it be handy!
I look forward to seeing your app. No pressure though, I would prefer wait and be amazed than have to experience the opposite scenario (the politically correct way to say "get to work, I am waiting" lol).
Thanks for the great work and excellent support!

Groupy

[Rob F]

Yeah I agree, a momentary switch option would be nice, quite a few people ask about it for feeding or maintenance.

I am happy with the app so far, its been running reliably for a long time now so it's just a matter of getting all the features loaded. I'm the type that likes to work on it 8-12 hours a day rather than an hour here or there which is why it's been a little slow lately but I'm happy to have it running full time so I can monitor and soon enough I'll be deep in it again. :)

[mathygreen]

Firstly Introduce myself. Long time freshwater tank keeper/Sunday afternoon tinkerer. Been using my Digital A'quit'us controllers till they couldn't the job anymore they had a good run). Been reading and researching the Apeck$ system but am holding back on forking over 2.5k. Now I am here, so well met to all, especially Rob!

I've been reading, trying to get to know this system (options, quantities, lengths, limitations, etc.
I got three questions that I haven't found definitive answers to.

1. What are the length limitations on the DB9 and ethernet cables? What lengths have been confirmed functional?

2. Does every pin on an extension module need to be connected? I assume not. I ask this not to waste some GPIOs. Example, I take a 6sensor/2DC extension, wire the ground, 4 sensors and the DC control pins to this first extension, then splice the gound.

And the other 2 sensor pins to another extension which would be 40 feet of wire away.
Of course both would have their own power supply. How about splitting a DB9 on 2 power bar extensions?

3. About the 15 meter DS18B20 on sale on the Robo-Tank website, is using this better than sending an extension with sensor input 14m away with a 1m DS18B20? Does one way deal better with interference and any other possible distance related problem?

These 3 questions are all related to having part of the Robo-Tank system 35 to 50 feet (as a wire is routed in my basement ceiling with house mains in the way) away from the controller board.

Minimally I would like temp and outlets. Maybe I can get away with sending DC signals down to SSRs instead of outlets but temp is a must. Sensor inputs would be a really nice to have.

Reliable Permit Solutions, LLC

[Rob F]

Hi mathygreen, thanks for signing up and those are good questions.

I've tested various extensions with 50 feet of cable, that includes the AC power bars, sensor extension, equipment extension, 6 DC / 2 Sensor module and the 6 sensor / 2 DC module as long as those have their own power supply as you mentioned. No current is sent through these lines so voltage drop isn't to serious of a problem but it was starting to drop at 50 feet. With that said the sensor extension is powered through the RJ45 so current is supplied to power the sensors but they don't draw much either however I think AC power bars could be extended further due to this.

The two DB9 connectors and the sensor RJ45 on the main controller are a direct connection to the Pi GPIO's with no circuit. I did it like that to keep it as flexible as possible. Due to that if you took a 6 sensor / 2 DC extension you could connect only the ports you need to the output pins on the DB9's, that would leave you the extra GPIO's to do anything you want.

I haven't tried splitting a DB9 but I think that would work. For example if you ran a DB9 to a to a 6 sensor / 2 DC then split it and down the line added another 6 sensor / 2 DC they should both work in sync. That would allow you to use some ports in one location and the remaining in another without cutting up wires etc.

For the DS18B20 the results would basically be the same using 15 meter sensor vs extending the sensor extension. The DS18B20 is susceptible to noise so it might be better to extend the sensor module as the Ethernet cable is twisted which might help but I can't be sure. It's also possible to get shielded Ethernet cable which could help in noisy environments. If the DS18B20 cable runs along AC power cables it can be a problem especially if the AC device has a large motor, at that point you would want some shielding.

The sensor extension that plugs in the RJ45 can run DB18B20's however the 6 sensor / 2 DC and 2 Sensor / 6 DC extensions won't work with them so that's something to consider.

If you can draw out a simple diagram on what you want and distances I can be more sure but I don't think you'll have a problem.