Invacare DX-REM24SC remote with CANH fault

Power wheelchair board for REAL info!

POWERCHAIR MENU! www.wheelchairdriver.com/powerchair-stuff.htm

Invacare DX-REM24SC remote with CANH fault

Postby fkopac » 04 Sep 2020, 08:31

Hello and thank you for having me :)
I have an old Invacare wheelchair we are trying to make usable again for a disabled person with no health insurance in collaboration with a local charity.
The chair was donated and looks to be from 2002, the joystick is DX-REM24SC. Reportedly the (very old) batteries were bad, so I replaced them. It turns on, but only works for a few seconds before the error light starts blinking.
I get the 10 blinks error code (CANH bad) so I hooked the CANH line up to a scope and sure enough, I get some activity on CANH for a second or three (varies), but then it stops and I get a 9.6V slightly noisy voltage (when the blinking starts). AFAIK you should never get upwards of 5 V on the CAN bus.
I do have experience in electronics and it seems like the smaller PCB inside is where the CAN-communication (and the problem) happens. There is no visible damage. The TXD and RXD signals are correct on the micro controller pin, but it gets distorted somewhere on the path to the connector of the small PCB - there are a bunch of small MOSFETS connected, probably driving the lines. I was thinking about severing the PCB traces and splicing in a new CAN transceiver, but want to try a more reversible solution first, if there is one.
Do you have any pointers on how to repair this?
For example, I could use a circuit diagram for the controller in case one is out there.
Do you have maybe a source where I could buy a used replacement remote? I understand that this would require programming it and I can probably get some pro-bono help from a local service there. Also, can you replace the DX-REM24SC with a DX-REM24SD remote?
I would be most grateful for any help and/or info ...
Best regards, Franci from Ljubljana, Slovenia
fkopac
 
Posts: 5
Joined: 04 Sep 2020, 08:04

Re: Invacare DX-REM24SC remote with CANH fault

Postby woodygb » 04 Sep 2020, 09:07

Circuit diagrams are not available.

I'd suggest finding a replacement for the defective control .

A special version of the Wizard programming software is available.
dynamic hirose interface rhino ssm.jpg
An expert is a person who has made all the mistakes that can be made in a very narrow field.
Niels Bohr
User avatar
woodygb
 
Posts: 7068
Joined: 12 Mar 2011, 18:45
Location: Bedford UK

Re: Invacare DX-REM24SC remote with CANH fault

Postby LROBBINS » 04 Sep 2020, 09:37

Before doing surgery on the REM, I'd suggest carefully checking the DXbus cables and connectors (carry +24, battery ground, CANhi and CANlo). Noisy messages can create great confusion! Cables are relatively inexpensive, and can be bought from www.rosstron.com (no web sales, so you'll need to send them an e-mail). If you're not in the U.S., you might want to find a Dynamic distributor where you are. If you do need a new can sub-board, PM me and I'll give you contact information for a couple of Dynamic engineers. I don't know if company policy will allow it, but they might be able to get you a board (especially given the user's situation). If you do decide to change the transceiver, be aware that at some date the TI transceiver Dynamic had used became obsolete and they switched to a newer TI transceiver. So, if you can't find an exact replacement, you might have to do the same, but I don't know if any board or firmware changes were needed for the newer transceiver.
LROBBINS
 
Posts: 5543
Joined: 27 Aug 2010, 09:36
Location: Siena, Italy

Re: Invacare DX-REM24SC remote with CANH fault

Postby fkopac » 04 Sep 2020, 09:56

Thank you both for this info :)
I did the testing on standalone controller (PSU instead of battery, only scope probes, no cables), so cables are for sure not the problem.
I'll wait if there are other suggestions and then I'll look into replacing the transceiver. I have some Microchip ones lying around, I just have to check if they are compatible with the way the CAN interface is done on the microcontroller. But first I'll try to read out the settings using the interface info you gave me, in case I break something and have to buy another one anyway.
@woodygb: You probably refer to the Dynamic Control Wizard 6?
fkopac
 
Posts: 5
Joined: 04 Sep 2020, 08:04

Re: Invacare DX-REM24SC remote with CANH fault

Postby woodygb » 04 Sep 2020, 10:07

Wizard 5.

You have a message .... scroll to the top of the page left hand corner .

IF your joystick pod has a 5 pin Hirose then the Coms is RS232...However if it is via the 3 pin charging socket it is a strange protocol.

The Dynamic signal protocol is weird...

It may look like a RS-232 serial but it's not RS-232 standard.
It is Serial comunication alright but neither RS-232 nor TTL logic levels!
It's more like TTL-serial with CMOS voltage levels.

Logic level 0 = 1-2V
logic level 1 = 10V

TTL
logic level 0 (LOW) = 0-0.8v
logic level 1 (HIGH) = 2v-5v

while the RS-232 levels are

Logic 0 = anywhere from +3 to +25V.
Logic 1 = anywhere from -3 to -25V (negative voltage)

On most PCs these signals swing from -13 to +13V.

CMOS gate circuits have input and output signal specifications that are quite different from TTL. For a CMOS gate operating at a power supply voltage of 5 volts, the acceptable input signal voltages range from 0 volts to 1.5 volts for a “low” logic state, and 3.5 volts to 5 volts for a “high” logic state. “Acceptable” output signal voltages (voltage levels guaranteed by the gate manufacturer over a specified range of load conditions) range from 0 volts to 0.05 volts for a “low” logic state, and 4.95 volts to 5 volts for a “high” logic state:
Image
An expert is a person who has made all the mistakes that can be made in a very narrow field.
Niels Bohr
User avatar
woodygb
 
Posts: 7068
Joined: 12 Mar 2011, 18:45
Location: Bedford UK

Re: Invacare DX-REM24SC remote with CANH fault

Postby woodygb » 04 Sep 2020, 10:39

@ fkopac ...CHECK YOUR MESSAGES.

messages.png
An expert is a person who has made all the mistakes that can be made in a very narrow field.
Niels Bohr
User avatar
woodygb
 
Posts: 7068
Joined: 12 Mar 2011, 18:45
Location: Bedford UK

Re: Invacare DX-REM24SC remote with CANH fault

Postby fkopac » 04 Sep 2020, 10:47

Thank you
fkopac
 
Posts: 5
Joined: 04 Sep 2020, 08:04

Re: Invacare DX-REM24SC remote with CANH fault

Postby LROBBINS » 04 Sep 2020, 12:31

Hi again. After writing my last note I wondered if pack-rat Lenny hadn't saved some bits and pieces from when Rachi's chair had a DX system. Indeed I had, and at least one module should have a good CAN board. If you'd like I'll dig that board out of an attendant control unit (which I think has a dead joystick) and mail it to you (from Italy). Let me know.

BTW, you may be able to substitute an MCP transceiver for a TI transceiver, but this board may have a controller/transceiver in which case no. My memory is that the TI controller has a FIFO input buffer, while the MCP controller has two single input buffers with different priorities and several masks available for each. Indeed, although the physical protocol is the same, even just the transceivers may not be interchangeable if they use different pins e.g. for sleep.

I also do have some other pieces: two 4-switch modules (probably both good), two dead PMs, one Specialty Controls Remote (functional when last used), one CLAM (combined lighting and actuator module), and a bunch of cables, some never used, etc. If anyone here can use any of this, let me know. I may have to ask you to cover shipping cost as some of this is pretty heavy (esp. the CLAM).
LROBBINS
 
Posts: 5543
Joined: 27 Aug 2010, 09:36
Location: Siena, Italy

Re: Invacare DX-REM24SC remote with CANH fault

Postby fkopac » 04 Sep 2020, 13:58

Dear Lenny, thank you for this :) I would appreciate it very much, but will first try to repair myself and bother you only if that doesn't work. I will get back to you by PM in any case.
I don't think the board has a transceiver as such, only level shifting, so the simple Microchip driver I have should work, but obviously I need to check (when the day job is done ;) ).
fkopac
 
Posts: 5
Joined: 04 Sep 2020, 08:04

Re: Invacare DX-REM24SC remote with CANH fault

Postby fkopac » 19 Sep 2020, 18:01

Hello everybody, just to follow up on the whole story:
I was unable to repair the remote. Although I had good looking CAN signals it seems the MCP transceiver was not powerful enough to work instead of the original circuitry.
So I found a used DX-REM24SD on e-bay for a fair price where the seller assured me it has the same guts and should work.
When it arrived, it was happy to see that it works, but it had a slightly different mount. I was thinking about making a replacement holder, but I saw that the ...SC and ...SD remotes have very similar looking bottom parts of the housing (where the mount is). So I moved the bottom part from the old remote to the new one (it's now a chimera!) and did not need to fuss about with the holder.
@woodygb: Thank you, thank you, thank you, I was able to reprogram the remote to work on first try :worship
I drove it around my house for a kilometer or so and everything seems in order.
Unfortunately the intended user is in a hospital right now, but I will be able to deliver it immediately after he comes out.
Again, everybody, thank you for your help, I really appreciate it. And if anybody needs an old attendant control unit or the joystick from the old remote, let me know.
fkopac
 
Posts: 5
Joined: 04 Sep 2020, 08:04

Re: Invacare DX-REM24SC remote with CANH fault

Postby woodygb » 19 Sep 2020, 18:38

:thumbup:
An expert is a person who has made all the mistakes that can be made in a very narrow field.
Niels Bohr
User avatar
woodygb
 
Posts: 7068
Joined: 12 Mar 2011, 18:45
Location: Bedford UK


Return to Everything Powerchair

Who is online

Users browsing this forum: LROBBINS and 88 guests

 

  eXTReMe Tracker