PC MeterBus Adapter FYI

bajasurfer
bajasurfer Solar Expert Posts: 30 ✭✭
edited March 2017 in Solar Beginners Corner #1
After getting the run-around since October 2008, instead of Morningstar providing the adapter for free as discussed in this forum, I was ultimately sent a link to where one could be purchased:

http://store.solar-electric.com/mopcmeadm.html

new link https://www.solar-electric.com/mopcmeadm.html

With shipping, that piece now runs over $40. How it could go from free to such a lofty price point is impressive, indeed.

If anyone knows of a lower priced alternative, please share.

Thanks,
Larry A

Comments

  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: PC MeterBus Adapter FYI

    I don't recall them ever saying it would be free, but the original price was supposed to be less.

    And BTW, it took almost 5 months from the time it was announced before they actually shipped us some. I suspect they ran into problems with the original (too cheap?) version.

    It is basically just a phone line RJ11 serial adaptor, but not sure if the pinouts on the ones sold in computer stores are the same.
  • Solar Guppy
    Solar Guppy Solar Expert Posts: 1,989 ✭✭✭
    Re: PC MeterBus Adapter FYI

    Its much more that the connectors, it has active buffers and opto-isolation internal to the shell

    For whats in the unit, its a fair price for true opto-isolation of the charger to PC connection, similar products sell for much more that do RS232 electrical isolation which are similar in function, MorningStar is selling basically at cost to the distributors I believe.

    SG
  • bajasurfer
    bajasurfer Solar Expert Posts: 30 ✭✭
    Re: PC MeterBus Adapter FYI
    Windsun wrote: »
    I don't recall them ever saying it would be free, but the original price was supposed to be less.

    And BTW, it took almost 5 months from the time it was announced before they actually shipped us some. I suspect they ran into problems with the original (too cheap?) version.

    It is basically just a phone line RJ11 serial adaptor, but not sure if the pinouts on the ones sold in computer stores are the same.
    A search on "modbus" yielded several threads mentioning the adapter was provided for free to people with valid serial #'d products compatible with it. Below are 2 of them:

    http://forum.solar-electric.com/showpost.php?p=19330&postcount=20
    http://forum.solar-electric.com/showpost.php?p=20399&postcount=4

    My initial inquiry was submitted to Morningstar in Oct... it appears that only early adopters benefited from their generosity. I don't have a problem paying for the part, but when I see a part go from free to $40, it makes me wonder. It doesn't make anyone else wonder?

    Insofar as similarity to standard PC terminal adapters, I reviewed the pinouts on the DB-9 side & they are identical to the ModBus adapter, but the RJ-11 side could not be verified. Besides that, the standard PC terminal adapter probably doesn't include the warp drive that Solar Guppy mentioned. I won't do a smoke test to find out; but if anyone else wants to, by all means, tell us what happens!

    Thanks,
    Larry A
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: PC MeterBus Adapter FYI

    although i agree that it could've been mentioned even in an announcement that only so many would get this for free if it was known it was free for only a short period and to be priced at $x later that you should note each of those comments were made some time prior to your attempt so it isn't like it was said 1 day and the next day it was being charged for.
  • Windsun
    Windsun Solar Expert Posts: 1,164 ✭✭
    Re: PC MeterBus Adapter FYI

    Well, I need to revise my original statement. We were supposed to get a bunch of these in about 1-2 weeks ago, but they still have not arrived.

    Not sure what is going on with the delays, will have to make some calls.
  • yoong
    yoong Registered Users Posts: 1
    Re: PC MeterBus Adapter FYI

    Hi:

    Has anyone try to find out the pin assignment for the MSC adapater? Can I use the normal plugs with pin assignment as below?
    Attachment not found.

    Regards
    Yoong
    a.jpg 66.3K
  • photovoltaic
    photovoltaic Solar Expert Posts: 37 ✭✭
    Re: PC MeterBus Adapter FYI

    I don't think you can just use a straight through cable - there are some electronics in the adapter cable supplied by Morningstar . It is doing some kind of signal conversion I believe. I was going to try and find out if I could build one myself instead of buying one but finally just gave up and ordered one.
  • smatthew
    smatthew Registered Users Posts: 15
    Re: PC MeterBus Adapter FYI

    I'm fairly certain the MeterBus is ModBus/RS485. The Serial port in your computer speaks RS232. Amazon has some extremely cheap RS232/RS485 converters - maybe try one of those first?
  • RandomJoe
    RandomJoe Solar Expert Posts: 472 ✭✭✭
    Re: PC MeterBus Adapter FYI

    I recently looked into the interface details, now that I have a SureSine and SunSaverMPPT thought I'd see if I could just get a 232/485 converter and do multidrop with them. Morningstar's docs suggest to me the Meterbus / modbus port is not RS485. It is switchable so the protocol spoken is Meterbus (proprietary) or Modbus, but that doesn't mean the wireline signals are RS485. Their communications document shows even for an RS485 multidrop configuration you have to use the MSC, and then a 485/232 converter to attach it to the 485 link.

    I didn't bother to check any further, though.

    As for the 6-pin cable pinout, I found it but now I can't remember where... It was a 2-page doc, thought it was the MSC instruction sheet, but the only PDF I have is just one page and only lists the RS232 pinout. The 6-pin pinout was on the second page! Anyway, it was simple enough - center two pins are the serial link, outer four are power. Two pins on one side are +12V, the other two pins are GND. The MSC is powered through the RJ11 cable. (Actually, ONE SIDE of the MSC is powered this way. The RS232 side is powered via RTS/CST pins.)

    Their docs also say to use the supplied (very short!) cable with no further details. I crimped some 6-pin ends on a run of CAT5, have the MSC about 25 feet away from the MPPT, works just fine. Note they have a funny (to me) definition of "straight through cable" - which is how they describe the RJ11 cable. It's actually a "standard telephone cable" wiring - if you hold both jacks in front of you, side by side, in the same configuration (say, pins up and facing away) the colors are mirrored. Perhaps that's "straight through" in phone company language, I'm more familiar with networking where "straight through" would have the colors in the same order on each end.

    I already had one MSC for the SureSine, and have plenty of USB/serial adapters for the monitoring computer, so just ordered another MSC for the MPPT. Might get more annoying if I were to have a whole bunch of Morningstar devices to hook up, but just two is fine! :roll:
  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: PC MeterBus Adapter FYI
    RandomJoe wrote: »
    It's actually a "standard telephone cable" wiring - if you hold both jacks in front of you, side by side, in the same configuration (say, pins up and facing away) the colors are mirrored. Perhaps that's "straight through" in phone company language, I'm more familiar with networking where "straight through" would have the colors in the same order on each end.


    Yup. That is straight through in that if you lay the cable out flat the two ends both have the tabs on the modular connector facing up (or both down). And if you construct your female-female couplers by setting two jacks back to back and wiring straight across, the result will be that any cord made from an arbitrarily large number of standard couplers and standard cords will be a standard cord.

    The result of all of this is that the jacks prewired into junction boxes and those wired into phones will be opposite in pinout. That works when there is a clear hierarchical direction between "central office" and "user equipment".
    SMA SB 3000, old BP panels.
  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    Dragging this from the dead only because I found it while searching for a Meterbus interface circuit. Never did find one, but did end up getting an MSC and reverse engineered it. It is NOT RS-485. It's basically a TTL level, open collector, bidirectional bus. Here it is. Should be right, but no guarantees.


  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Thank you Mike... And welcome to the forum.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset