poking rs232 port BMS

I've got a battery management unit that is reluctant to demonstrate functionality. The vendor's terminal com software seems non-functional (will not install).

So far the only evidence of life is a control line (one of three) hard on, and rare /XFFE /FFF signalled outputs on the rs232 port. Internal DC-DC fails to power LEM sensor. Balancing terminals seem inactive.

Can anyone recommend a tutorial on poking a serial port for status / data register contents ?

It should be reporting on the voltage of four LiFePO4 batteries, powering a LEM sensor and reporting current. Many other undocumented features for I/O via remote terminal. Has CAN port, which seems to be used only for control power and crude 'run' (input) /'stop charging' (output) LF/DC signals.

I'm in touch with the overseas vendor, but they seem reluctant to comment on their SW functionality or test criteria for the unit. Outgoing photographs and diagrams from here, mostly, so far. The manual and it's diagrams don't make much sense, refering to non-existent hardware or unavailable interface modules.

Someone has gone to a great deal of trouble to chart the identity, labelling and function of I/O terminals, but these are largely ignored in subsequent diagrams or instructions.

Mostly used in SE Asia or the Indian subcontinent. English version is only recently available.

RL

Reply to
legg
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Maybe rely on user forum threads in Asia / India, using Google translation, is that a viable option?

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Reply to
Winfield Hill

X FFE/FFF smells of baud rate error... Is that a possibility ???

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Reply to
TTman

Random 0xFF characters are often a sign of false start bit ("0"), but the voltage returns quickly back to idle "1" state. A false start bit has to be about 0.5 to 1.4 bit times to produce 0xFF and 1.4 to 2.3 bit times to produce 0xFE.At 9600 bit/s that would correspond to 60 to 230 us long positive going noise pulse.

Reply to
upsidedown

TTman wrote in news:qps1nb$8rt$1@dont- email.me:

For stuff like this, folks should remain in the single baud mode of less than 9600. Work out all the bugs before you try higher rates. Higher handshake rates should be left out.

That might fix the entire problem. How much data are these ports trying to pass in a given datagram event? IOW is a high data rate even needed at all?

Reply to
DecadentLinuxUserNumeroUno

I'm interpreting it as the BMS kicking the RS232 tx line, looking for life at 'my' end - signs of a possibly working terminal in the BMS. They accumulate at a rate of ~once every half hour or so.

It's the simplest of 3wire connections - rx, tx and gnd, with no other pins offered on the port.

RL

Reply to
legg

The tech support is supposedly forwarding a new version of the software (mewyeah.exe), but seems to forget to attach it, or provide a link to it, in his correspondence.

His e-mails/texts hit around 3.30 in the morning here. I've suggested that 8pm NA / 9AM SEA might be more productive.

Luckily, there's more than one workbench here, and more than one datalogger harness. Three serial ports being hogged for this.

Just my luck if it turns out BMS can only communicate on lower port numbers.

RL

Reply to
legg

All manual references fall back on 9600. It's not noise. /xffe or /xfff could just be the monitor having difficulty with half-hour spacing between the characters. It read /xffc, once.

Simple 3 wires are all that's available.

RL

Reply to
legg

FF is a single narrow pulse on the data line FE is a slightly wider pulse, are you sure you have the baud rate set correctly? uising a too low rate can cause this.

poke at it with leds and resistors, or theres software that can do that too. I use statserial.

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Reply to
Jasen Betts

What sort of serial poert are you using that handles 12 bit symbols?

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Reply to
Jasen Betts

I've seen software that could only communicate on ISA-bus serial ports :(

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Reply to
Jasen Betts

Maybe it's modbus where you have to hit it with an address, a command, data and a CRC to get it to respond correctly ?

OR some other proprietory system but still may need prodding to respond ?

Modbus and CANbus is common for BMS's as far as I know but other systems exist too of course

Reply to
boB

One option: Get a RIGOL oscilliscope with the free "advanced trigger" options installed. There's one on sale right now for around $300. (at TEquipment.net)

You can decode the bus, (inverting if need be).

We do a lot of RS-232, 485 and Modbus stuff here, and lately my Rigol DS2072A has been a life-safer for weird comm problems.

Good luck. BTW: I just posted a similar Chinese problem regarding a new laser etcher we got, so I feel your pain. You would think for all the tariff dollars flowing out of bank account we would at least get a User Manual in English!?

As for Chinese software, I've always wondered which works best: The actual software, or all the spam-hack virus bloatware it loads.

Reply to
mpm

Just had J1939 dumped in my lap. I'm afraid that without mfr's com SW, it is beyond a bit of poking.

RL

Reply to
legg

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