Huawei R4850g2 can bus voltage control

hi i am trying to control a huawei power supply through can bus and i am trying to verify that the RS485 standard pinout as shown here with the A+ and B- is the same as the CAN H and CAN L seen in the RS232 standard that i see in this video of someone controlling the same power supply.

here is the RS485 adapter

should note that i was planning on controlling it internally not through the can bus lines as detailed in this video at around the 10 minute mark but the reason i am not doing this is because when i got the power supply my board is different so i will keep the adapter in case i need it for anything else.

please see attached picture of my board above this text for reference and look at the one in the video if you are interested in the other route.

i will be using this code through linux

this is the link to the video of the guy controlling it and this is the RS232 usb converter.

here is also a link to one on aliexpress
(sorry for the big url)

help would be appreciated regards jesse


Hi Jesse

No it is not.
RS232 is unbalanced.
RS485 is balanced.
The 2 are quite different in operation.
At a guess without looking at data sheets looking at the chip types in that converter that the USB is converted into RS232 and that is then converted into RS485 for transmission, usually over longer distances up to about 1200 metres. You then have to convert the RS485 to whatever you need at the other end.
If your transmission distance is only couple of meters RS232 should be OK . Longer runs can be obtained but low capacitance cable and different wiring technique required.
Cheers Bob
Just had a look at the top video.
Don’t like the soldering technique much. Iron seems way too small to solder the large copper tabs. He might have soldered the edge but I very much doubt the flat part will be soldered very well. The tabs on the power supply appear to be gold plated. If so the gold should have been removed or there is a very good chance the connection will fail.
If you try something like that I hope you use something like a large 100W iron for a start. To remove the gold plating tin the pad with solder then remove by wiping all of the solder off. Do this 3 times and this usually will remove a fairly heavily plated surface.
Cheers again Bob


thanks bob for all the info will see how i go and post what i did as the run is only literally next to the power supply i will use the RS232 and follow the guy who was controlling thr voltage on the power supply via his computer.

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ps the tabs are indeed gold plated on the power supply i will upload a picture of the adapter the can bus controller guy used as i have a similar one in the post atm.
also schematix did indeed say that his soldering iron was to small i however do indeed have a bigger butane one i also have a small one for all the small stuff.

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Hi Jesse
A tip. If you are going to fit and solder copper tabs as in that video tin the inside surface (the bit you can’t get at later) that you are going to solder first before you bend it. Wipe all the excess solder off with a cloth just leaving the shiny surface. This will give you a better chance of a good solder connection over the whole area. I did notice the guy in that video did not do this or remove the gold and combined with a small iron it will be anybody’s guess what the connection is like.
Don’t bother plastering all that resin flux over the gold. Not needed. Gold is a noble metal and does not tarnish. That is why it is used in connectors.
Cheers Bob

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Hey Robert,

Don’t mean to derail the conversation here, but that iron he’s using is a TS80 (possibly TS80P). They range from 18W to 30W, which seems like not much, but the temperature regulation is great as there’s a microcontroller doing PID on a MOSFET attached to the heater, and the heater is jammed right up against the tip. It’s still not as good as a JBC or a direct-heat Hakko, but they aren’t bad, especially when you consider they can be run off a USB PD power bank in a pinch.

EEVblog did a video on them a while ago and found that they can be coerced into tinning big copper things, but it isn’t ideal:


Hi James.
Looked a bit small that’s all.
I have usually found that Watts is Watts is Watts etc and a 30W iron does not recover too well when soldering big bits and took too long with the danger of damage because of the extra time.

We sometimes had to solder solid copper sheath co-ax cable to a copper ground plane and found if a larger iron was not available a better result was achieved by using 2 irons (two people required of course).
Another scenario, do you remember the large PMG style “Chocky Block” terminal blocks with the large thick pins. If you had a lot of pins to solder a 30W iron was a bit of a pain and we found 80W or 100W iron the best as you didn’t have to stop every few pins to let the iron recover.

That is a nice looking iron for that size. I will do a bit of research and find out some more. Thanks for the info.

Personally for that size of tool I use a temp controlled Goot which I find OK. I needed a bit larger tip that is available for my model and finished up getting a tip for a different model which is too long but got a fitter mate to shorten in his lathe and works OK. For larger work I use an 80W 240V Weller.
Cheers Bob

Just had a look at that video. That iron is far too small to solder that size wire. Contrary to what the movie star says it is NOT doing a good job. If you look closely is taking too long (which I why I usually advise using a large enough iron) and the solder is “wicking” back up the wire like a sponge. Not good practise and if I did that on most of the jobs I did it would have been flatly rejected.
Cheers again Bob


Hi Robert,

Good to hear a pro’s opinion on the video’s tinning performance! Out of interest (for someone like me that never has to tin wires that big) Why is the wicking bad? (at a guess I’d imagine it’d break up in the wire if you flexed it or something like that)

Keen to hear your thoughts!

Hi James

Exactly right. The wire WILL break just where the solder finishes. If this happens it is easy enough to find really. Just give the wire a tug and the insulation will stretch where it is broken. For some reason if no wicking occurs the wire doesn’t seem to break. May be due to the insulation restricting slight wire movement more than where the wire is bare. Wicking has to be avoided when soldering into connectors where a bit of flexibility right down to the connector pin might be desirable when fitting into a Backshall. Some high reliability procedures stipulate a copper heat sink be used right at the connector solder bucket and keep the solder where it belongs. I have never seen one but Have heard of water cooled heatsinks for this purpose. Seems like a bit of overkill but for super high reliability and if the specs say do it us mere mortals can’t argue. In practise I have seen the adverse results of this wicking and I can vouch for the merits of paying attention to detail.

When you have a connector of pretty high density (the multi pin circular military types come to mind) all this becomes somewhat awkward. Royston produce a very good soldering tool for this sort of thing. Like a pair of tweezers where you can hold the wire in the solder bucket. A current is passed through the job and the only part that gets hot is the joint point itself. then the joint can be done properly by applying solder directly to the joint as it heats. Note. The practise of transporting solder to the job on the iron is also a no no. With this tool wicking is non existent

AWA Standard Practise Manual stated that the insulation had to be no more than 1/16 inch from the joint so as you can imagine you had to take great care to prevent wicking.

All this makes a good case for crimp connectors. But there are still some provisos. You need the correct pin for the connector, it has to be correct for the wire size and when you have decided on that you need the correct tool. If you have all that there are a couple of main advantages. You will not get a bad or dry solderer joint, you will not have any wicking problems.
Cheers and enjoy the rest of your day. Maybe revise some soldering techniques.