CANopen and SDO Download - ACK Message?

[bc_fred]

We are working with a Vision 350 PLC and a KollMorgen Linear Actuator Controller. We have to modify the PDO messaging contents to expand the list of values that are sent and received. We have a complete listing of the change messages that we have to send to the Actuator.

We are using SDO Send STR and SDO Receive STR. Without a sniffer, it's hard to determine the exact contents of the outbound string message, but we know exactly what we have to put into it. Apparently, there is an ACK message that we get back each time, and we have to listen for it.

I have read fantasia's document about talking to the robot and I see that there is an SDO Receive STR after the Send STR. She then compares the resultant received value to zero. If zero, all OK, otherwise, error. I've also read Tim Moulder's excellent documentation, which is greatly appreciated.

Questions:

- The ACK message comes back as a hex string. Can I view, somehow, the exact hex string returned?

- Do I have to wait for an ACK containing zero in the data bytes before sending the next SDO Download STR?

- Does anybody know the difference between "Domain Segment Transfer" and "Block Segment Transfer" in Parameter D of 'SDO Download STR'? Anyone at Unitronics??

Thanks for any and all kind words.

Regards,

Fred Mason

Crosswind Power Systems Inc.

[Ofir]

Hi,

As you already mentioned you can check in SI225 (SDO status) that there is no error (equal to zero).

There is another system bit SB243 which indicates SDO transfer failed when it is on.

Please note that the PLC has CAN sniffer built in inside INFO mode where you can see all transmit and received CAN messages!

Using the new VisiLogic 9.3.0 you have also the option to sniff all received messages to a data table - Please help topic CANbus Message to Data Table.

Please see detailed information about the difference between "Domain Segment Transfer" and "Block Segment Transfer" in the below link:

http://www.softing.com/home/en/industrial-automation/products/can-bus/more-can-open/service-data-object/download-sdo-segment.php?navanchor=3010619

[bc_fred]

Hi,

As you already mentioned you can check in SI225 (SDO status) that there is no error (equal to zero).

There is another system bit SB243 which indicates SDO transfer failed when it is on.

Please note that the PLC has CAN sniffer built in inside INFO mode where you can see all transmit and received CAN messages!

Using the new VisiLogic 9.3.0 you have also the option to sniff all received messages to a data table - Please help topic CANbus Message to Data Table.

Please see detailed information about the difference between "Domain Segment Transfer" and "Block Segment Transfer" in the below link:

http://www.softing.c...vanchor=3010619

Thanks much for your reply. I must admit that I read your link regarding the Domain vs. Block Segment distinctions and I don't understand it. I have looked at the sniffer in Info Mode, but it would be much more useful to copy to a table as you indicate in Visilogic 9.3.0.

We bit the bullet and ordered a sniffer. I will let you know how we get on with our experiments.

Thanks again.

[tmoulder]

We bit the bullet and ordered a sniffer. I will let you know how we get on with our experiments.

Thanks again.

Good decision