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CANbus option

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I'm planning to order the 12kW unit. Looking at ordering options I see an option for CANbus, which I'd be very interested in.

Do you have any protocol details for this option? I have a BMS which uses J1939 style 29bit, 250kbps, protocol.

I'm interested in integrating the BMS with the inverter, such as commanding charge start/stop, target charge voltage/current, etc.


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5 hours ago, electric1 said:

Looking at ordering options I see an option for CANbus, which I'd be very interested in.

The real reason for the 3 options in that list?  Those are the available options with the isolated serial converter modules 😉.  In other words, the converter module you pick gets soldered onto the board while building the inverter -> out it goes.  (They're through-hole, not SMD.)

As of right now, there is no specialized protocol stuff written for the GS inverter for the link port on the new units...but I can of course easily add them via firmware updates.  As long as the hardware is there, the software can be updated in the field as necessary.  (MODBUS is the only item I've bothered with so far!)

If there's a "standard BMS" protocol (or if you can find a spec sheet for your BMS unit), I should be able to make that interface to the inverter.

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I work in the RV market where we use CAN protocol called RV-C, which is based on J1939. This protocol allows BMS-Inverter comms using just a couple of CAN messages. But your products probably better suited with SMA protocol, which is historically dominant in solar inverter market. Technically it's not an industry standard, there is no standard for CAN comms in the solar market that I know of, so SMA is kind of defacto standard because they were first in the game. Victron uses SMA in their BMS-Can interface, see attached PDF from Victron. The bare minimum you need is just message 0x351 where BMS tells the inverter what voltage and current not to exceed, for both charge and discharge. If and when BMS needs to protect the battery it would send current target = 0, which effectively means stop charging or discharging. Using this message BMS can effectively drive the charge profile stages, such as Bulk, Absorption, Float, where inverter-charger is just following BMS commands. Then, with further firmware development you can expand the list of supported messages with fancy alarms, status reports, etc. 

Also attaching SMA inverter manual with much more details about CAN protocol.

Many BMSs on the market are compatible with SMA, so you will find some happy customers if there is SMA support in the inverter. I'll be one of them for sure.

can-bus_bms_protocol 20210417.pdf SMA Inverter manual.pdf

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16 minutes ago, electric1 said:

I'm curious to learn what CAN controller IC it's based on and what transceiver is used.

I have no idea what the internal CAN IC is--as these are fully electrically isolated, potted/encapsulated transceiver modules, made by MornSun (Chinese company).  Expensive little boogers, but isolation on signal lines is almost a must for DC-based systems.

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