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@dhugoexe
Description
SDO Block Transfer fails with "Unknown SDO command specified" error
Hi everyone, I'm trying to send a binary file over SDO Block Transfer. I've created a Python SDO client that sends to an SDO server (ESP32-based CANopen node).
Environment
- Python canopen version: 2.3.0
- Platform: Windows
- CAN Interface: PCAN USB
Issue Description
The block transfer fails with error Code 0x05040001, Unknown SDO command specified. The server logs show a sequence error during the transfer.
Code to Reproduce
import canopen print(canopen.__version__) import os filename = 'data/data.bin' network = canopen.Network() node = canopen.BaseNode402(10, "path_to_od.eds") network.add_node(node) network.connect(interface='pcan', channel='PCAN_USBBUS1', bitrate=125000) filesize = os.path.getsize(filename) print(f"File size: {filesize} bytes") try: # Send file size filesize_bytes = filesize.to_bytes(4, byteorder='little', signed=False) node.sdo.download(0x2005, 2, filesize_bytes) # Send file data using block transfer with open(filename, 'rb') as infile, \ node.sdo[0x2005][3].open('wb', size=filesize, block_transfer=True) as outfile: while True: data = infile.read(1024) if not data: break outfile.write(data) print("Block transfer successful!") except Exception as e: print(f"Block transfer failed: {e}") network.disconnect()
Error output
Block transfer failed: Code 0x05040001, Unknown SDO command specified
ESP32 Logs
I (41404) CO_driver: CANRX id: 0x60a, dlc: 8, data: [35 5 32 2 244 0 0 0]
I (41413) CO_driver: CANRX id: 0x60a, dlc: 8, data: [198 5 32 3 244 0 0 0]
I (41422) CO_driver: CANRX id: 0x60a, dlc: 8, data: [1 0 0 0 0 49 57 55]
I (41423) CO_driver: CANRX id: 0x60a, dlc: 8, data: [2 48 45 48 49 45 48 49]
I (41425) CO_driver: CANRX id: 0x60a, dlc: 8, data: [3 84 48 48 58 48 49 58]
I (41431) CO_driver: CANRX id: 0x60a, dlc: 8, data: [4 53 50 0 0 0 0 0]
I (41438) CO_driver: CANRX id: 0x60a, dlc: 8, data: [5 0 0 0 0 0 0 0]
I (41444) CO_driver: CANRX id: 0x60a, dlc: 8, data: [6 0 115 121 115 116 101 109]
I (41451) CO_driver: CANRX id: 0x60a, dlc: 8, data: [7 0 0 0 0 0 0 0]
I (41457) CO_driver: CANRX id: 0x60a, dlc: 8, data: [8 0 0 0 0 0 0 0]
I (41463) CO_driver: CANRX id: 0x60a, dlc: 8, data: [11 50 53 45 48 54 45 50]
I (41470) CO_SDO: sub-block, rx WRONG: sequno=0B, previous=08
I (41476) CO_driver: CANRX id: 0x60a, dlc: 8, data: [17 0 0 0 0 0 0 0]
I (41482) CO_driver: CANRX id: 0x60a, dlc: 8, data: [23 0 0 0 0 0 0 0]
I (41488) CO_driver: CANRX id: 0x60a, dlc: 8, data: [31 128 63 0 0 224 64 0]
I (41498) CO_driver: CANRX id: 0x60a, dlc: 8, data: [197 81 178 0 0 0 0 0]
CO_SDO: sub-block, rx WRONG: sequno=0B, previous=08 -> Maybe a packet lost ?
EDS Configuration
[2005]
ParameterName=File transfert
ObjectType=0x9
SubNumber=0x5
[2005sub0]
ParameterName=Highest sub-index supported
ObjectType=0x7
DataType=0x0005
AccessType=ro
DefaultValue=0x04
PDOMapping=0
[2005sub1]
ParameterName=File name
ObjectType=0x7
DataType=0x0009
AccessType=rw
DefaultValue=0
PDOMapping=0
[2005sub2]
ParameterName=File size
ObjectType=0x7
DataType=0x0007
AccessType=rw
DefaultValue=0
PDOMapping=0
[2005sub3]
ParameterName=File data
ObjectType=0x7
DataType=0x000F
AccessType=rw
HighLimit=65536
LowLimit=0
DefaultValue=
PDOMapping=0
[2005sub4]
ParameterName=Transfert status
ObjectType=0x7
DataType=0x0005
AccessType=ro
DefaultValue=0
PDOMapping=0
Questions
- Is my Python code correct for SDO block transfer?
- Could this be a configuration issue on the ESP32 server side?
- Is SDO block transfer fully supported in the Python canopen library? I've seen that the feature might not work correctly on every implementation.
Thanks in advance for any help!