Modbus Holding Registers - more needed

[erblock]

Hello,

I have adjustable frequency drives (GE/Danfoss) that require reads and writes from/to holding registers with address of 50000, 50010 and 50200, 50210, etc.  The current Modbus object does not go above 400000 for holding registers.  I even have one document that references a 6 digit 5 series holding register of 500000.

Please confirm issue and propose resolution ASAP.  Basically, I will be unable to control speed and start/stop of many fan motors without this expanded Modbus register capability, so I would like a non-regression tested fix to test soon!  Both  6.1 and 6.2 versions of updated cbx needed.

Reference document pages attached

Thanks,

Ed

[erblock]

Please disregard the above post and this thread.  The registers mentioned are actually 4xxxxx series registers.... 450010, 450200, etc.  The programming guide did not document these registers (as shown in an obscure section of the design guide pages attached) and that is why I was confused, along with my normal mental issues...

Turns out these manufacturers also only used one in ten registers so I had to limit holding register read/write blocks to 2 instead of the default 125.  This allows reading 32-bit registers, but prevents reading registers that don't exist.  This significantly cloggs up my communication bus, but for now, I will have to deal with it.

I've never had such confusing documentation and Modbus RTU limitations from a manufacturer before, over many years and many products.  Oh well.....

Happy New Year!

Ed

[TomBaum]

Hi Erblock,

As I could read from your post you are using registers with adresses 4xxxxx. So 6 digits at all. Did you used the Modbus library in LabVIEW and can you tell me how this works? I mean which are the settings to use the normal adresses (5 digits) 4xxxx and the larger one (six digits)?

Thx 

TomBaum

[erblock]

Hi TomBaum,

I have not worked with Modbus using LabView, only because Lookout does such a great job and has all the register types and controls built in.  It should depend on your slave device register map I believe.  Some devices will give the same register data whether you use 5-digit or 6-digit.  I use 6-digit holding registers with most devices.

Good Luck

Ed

[TomBaum]

Thx for the info.