NABU RS422 Cable

I picked up one of the NABU Personal Computers, well two the first one was DOA for some reason. Shipping is prohibitive so I kept it for parts or repair. I just got the second one and it is working and displaying properly. To check it further and do anything useful with it I need to make up a cable for the RS422 to USB Adapter.

The adapter that is being recommended is a DTech USB to RS422/RS485 cable. I purchased mine from Amazon.

So the NABU has the 5Pin Din plug that needs wired up to the DB9 connection to the RS422 Adapter.

Cable Information from here:

To make the cable we just require a 5 Pin DIN Male Plug, a DB9 Female connector (and Shell/Cover to make it pretty), and a 4 conductor piece of cable, it is recommended to use a Shielded cable though as well.

Just a note on the “*Note:” from the source page above, the NABU 5 Pin DIN Adapter port “Shield” is wired to the AC Line Earth Ground Pin. I tested my DTech RS422 adapter the DB9 connector is not wired to the Ground Pin on the connector or the USB Shield. The Grounding issues are either when there is “No Ground” causing the effect of having “No Shielding”, or if Both the USB and the NABU Earth Ground are wired together you get a Ground Loop issue. The recommendations are to keep the cable short, ground the cable shield to the Ground pin of the RS422’s DB9 port (Pin 5 on the DB9). I don’t know the merits of grounding to the Cable Shield to the DB9 Pin5 compared to wiring it to the NABU 5 Pin DIN Shield which goes to the Earth Ground pin on the AC Cord. I also don’t think the cable is required to be nearly as short as recommended. We aren’t talking about using faster than RS232 signaling and common cable lengths for such uses were 6′ or longer.

So now we have the parts collected, it is time to wire it up. Then Test the cable that it is wired to match the diagram above and that there are no shorts etc.

I ended up using part of a scrap of shielded cable I had which had enough wires in it. I cut the length of cable I wanted to use. I slid on the “boot/cover” of the DIN Connector, I expect that just about anyone who has made cables has forgotten that at least once. I then stripped back the outer jacket, took back the shield, I folded back the couple wires I didn’t need and put heat shrink over the ends of the cable to hold those wires back and give strain relief to the connectors of the cable. The Shield Wire is still there, I did connect it to the DIN end of the cable. I did not connect the DB9 shell to the cable shield.

They said to keep the cable short, I made mine longer than “recommended” but kept it fairly short. My RS422 adapter has a short usb lead so I wanted enough cable between it and this one to let me still reach a computer on either side of the NABU.

Above the finished cable with the RS422 cable connected. I tested the cable several times to ensure it was correct. I then loaded the adapter software on my laptop and tested it. It worked properly the first time. I used the drivers that were provided on the mini cd that cable with the cable for Windows.

I guess I could have taken a picture of the NABU online. Maybe I’ll add that to the post here later.