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Write Control word, read status word Unidrive SP


At the moment I have the transmission type of the PDOs I've mapped set to 253d, which is RTR Only. The default transmission type is 255d, which will initiate transmission on a change of value.


What's odd is that I can read each register to which I've mapped a value and it returns the correct register address. If I mapped three objects to TxPDO 3, I can read the register address, sub-index, and size (16 or 32-bit), for each one, but the number of mapped objects register will still read zero.


I'm expecting a 9881 module today, I'm told that it's a CANopen module and thus I can make use of the NI CANopen library. I was also told that the cRIOCANopenBasics project code isn't strictly CANopen compliant. I don't know why or what problems this might cause, but I'm going to try the other module in place of the 9853 and see if that works any better.

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Message 31 of 34

 Try changing to only two mappings, I'll need to check but the default size on SP is 32 bits with compression off.


Either way try just two mappings and let me know if this works.


Remeber the PDO is 64 bits in size.



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Message 32 of 34

Hi everyone,


Nobody have a vi for sending a torque consign to a unidrive SP using RS485 serial (modbus RTU) ?


Thanks in advance.


Best regards,


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Message 33 of 34



This thread is regarding CANopen communication to a Unidrive SP. Perhaps it would be better to open up a new thread for RS485 communication, and include some extra informations such as the hardware you are using to communicate.

Daniel C.
Applications Engineer
National Instruments
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Message 34 of 34