RoadTest: RPI BC DIN rail housing for Raspberry Pi computers
Author: hlipka
Creation date:
Evaluation Type: Independent Products
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: BitScope Blade Uno: https://de.farnell.com/bitscope/bb01b/bitscope-blade-uno/dp/2546576?COM=referral-noscript
What were the biggest problems encountered?: Opening the lid when its closed once...
Detailed Review:
This was one of the road tests where the device to be tested was intended to be the main part of a project. So its not just about looking at it, playing around and doing measurements, this time it gets real 
Ever since I got my 3D printer (a K8200) I was bothered by the fact that it blocks my computer while printing. It needs my PC to run, and I'm always hesitant to get it under load when the printer is running out of fear it will ruin the print. So I got a Raspberry Pi with OctoPrint on it to run as print server. I already had a wooden board which holds the K8200 controller with its display, a 24V power supply and a "power PCB" (which creates the 15V for the controller and adjustable 12V for the fans). Unfortunately there was no room for the RPi anymore, so it was always laying around on the floor. And this nothing you should do to your Raspberry...
So when I saw this road test it looked it would be a natural fit.
I had already planned to use the LMZ36002 EVM to supply power for the RPi since it can run from a 24V input - this would then be the first time for me to combine two tests into one. I verified that the enclosure would fit into where I needed it to go, and the applied.
gschwarz already provided a great set of detail pictures in his road test, so I won't post any unboxing pictures here. Suffice to say that the packaging is quite good, but the documentation is a little bit lacking. You just get a small leaflet with assembly instructions, but thats it. All the other details are hidden in the hand book, especially the measurements for the PCBs you can insert into the enclosure. (it would have been nice to include them in the road test - Farnell doesn't sell to private persons here in Germany). Unfortunately there are no EDA files (e.g. Eagle or KiCad) available for the PCBs, just mechanical drawings (DXF files - e.g. for the small PCB which needs to be 85x83.5mm). So you need to create them on your own if you want run your own PCBs for the enclosure.
What's nice is that this PCB comes with header to connect the enclosure to a bus running inside of the DIN-Rail, so you can connect multiple enclosure together, or run the power supply from below.
You can also get a somewhat larger PCB (85x59mm), which is designed to fit into the RPi expansion header. So this is the one you should use when you build your shield. The vertical stacking header that comes with that PCB is probably also useful when you want to use a regular RPi extension board - provided that it only populates one side of the board (the one facing the RPi).
The larger board also comes with 4 90° connectors that go to the side of the board, and fit into a slot in the enclosure. These would be used for any external connections, and are matched by corresponding wire connectors (which seem to be of a self-locking construction, but I'm not sure since its not mentioned anywhere). Unfortunately there is no additional cover provided when you don't want to use all of the 4 connectors - in that case you have an open slot at the side.
The same is true for the other half (where the smaller board goes). There both sides are always open completely. Since the enclosure is designed to be mounted sideways, one of the holes would always face upwards, so you nned to be very careful when working at the switch board. Even when you turned off all power before, if can happen quite easily that some wire snippets fly into the case. So such covers are something that really should be added to the offering (even for the base enclosure).
I would also like to see a way so you can add a PCB filling the enclosure completely (which would be about 85x105mm), so you can realize bigger projects more easily. Also, the lid on the top seems pretty useless. You cannot see through it, and its not designed to be opened again when its closed. I cannot image where its needed for reaching anything after the enclosure was mounted. Some means to install switches or LEDs more easily would be much more useful.
This is what you see with the lid open:
Nothing useful to do here (except when you put some measurement pads on the PCB so that they can be accessed)
So my goal was to add a "power distribution board" along with then RPi. My old K8200 setup looked like this:
(with all the wires already removed - the PSU would go to the left).
This board uses a PTN78020H power module from TI to convert the 24V from the PSU to the 15V the K8200 controller uses. The 15V drive the board, the stepper motors and the hot end heating cartridge. The heated build plate is driven by 24V using an additional MOSFET. I also added adjustable regulators for two fans and one constant current sink for an LED ring.
To be able to run the motors and the hot end with 24V, I decided to change the controller board, and I'm now using a GT2560. Since the fans run with full speed anyway, I decided to skip the regulators and use the ones at the new controller board. I also switched to using a E3D hot end for 24V. So I just needed a 24-to-5V converter for the RPi and some means to distribute power.
Upon opening the box I immediately recognized that I should have verified my assumptions about the size of the enclosure beforehand - its just to small 
None of my two TI buck converter modules will fit - the LMZ36002EVM is too long, and the LM46002 is too wide. Time for some four-letter words
But soon I had a plan B, which just meant a little bit more work. I'm quite a fan of the TI Simple Switcher power modules, especially the LMZ1420x series. So I decided to use a small LMZ14203 board I made a while ago, which can run with up to 42V at the input and delivers 3A - this should easily be enough for what I want. And its just 25x30mm, so there is plenty of room. Thinking a little bit deeper about that, I also decided to put that spare room to some use and add a proper shutdown logic.
I put a Solid-State-Relay in front of my power supply, and programmed a PIC12F1822 to keep it powered until it gets a signal from the RPi to turn it of. That way, the RPi can not only turn itself off (as the usual shut down or UPS solutions for the RPi do), but can turn off the complete printer. And I can switch everything on with just a simple button press (but this is a project for a separate blog).
(Sorry, the LMZ14203 power module is hiding under that one connector)
There are several thing to note when you want to create your own project to go into this enclosure:
I actually managed to get the PIC program right in the first go, but when soldering I did cut some wires too short to have them end up where I needed them to be (power input and SSR to one side, power outputs to the other side). It would be nice to have proper covers for the enclosure, and I should actually use some good-quality 90° connectors instead of the wires coming straight off the board. But apart from that, everything went smooth, and the is still some room to spare.
Mounted in the enclosure, right before putting the lid on:
Here is my final setup:
(not mounted to the K8200 yet - click on the image to see more details)
The white box at the left contains the mains socket with attached filter, the SSR and the button to turn everything on (it just bridges the SSR so everything gets turned on, and then the PIC keeps the SSR turned on). To its left is the PSU, then the RPi, the GT2560 and the display.
From the sides of the RPi DIN enclosure:
(I'm using a RPi2, so I don't have WiFi on board and need an external dongle). The wires are dangling out of the case since I didn't have an good 90° sockets available which would fit in the provided space.
So would I buy this without a road test? Probably yes - its a very nice case for anything that goes into a fixed place (like a VDR, a OpenELEC box or a printer controller). For something that gets moved around the form factor is somewhat unwieldy, and for such uses the case really needs to be closed on yll sides. There is too much chance for damaging the electronics otherwise.
There is quite some room provided you can live the splitting your project into two PCBs. The documentation is OK (and for a RPi case its actually quite extensive). But I would wish for some EDA file because that makes it much easier to design your own boards (and this is where I see these enclosures).
Maybe Phoenix could provide a power supply that goes into the second half of the case and is powered from the DIN rail connector (or a 230V version with a C7 connector). That would be really useful. Also, some means to more easily mount LEDs and switches would be helpful. (Although there is a transparent lid so you could see LEDs mounted on the PCB)
