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Bug fixes, send/receive debug logs and Unsigned 24 support #267

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Bug fixes, send/receive debug logs and Unsigned 24 support #267

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5141b19
test if callback exist before removing it
TzviRonen Sep 6, 2021
3ce8ab4
Added send message debug log
TzviRonen Sep 6, 2021
bc06df4
Added debug logs and pause before read
TzviRonen Sep 6, 2021
3fb146e
fixed get_data var len calc
TzviRonen Sep 6, 2021
659899d
Added Unsigned24 data type
TzviRonen Sep 6, 2021
9b9efb7
Added PyCharm to gitignore
TzviRonen Sep 6, 2021
a8fcd87
request_response RETRY_DELAY
TzviRonen Sep 8, 2021
d0d9bba
made RETRY_DELAY default zero
TzviRonen Sep 8, 2021
b14f43e
removed callback test
TzviRonen Sep 8, 2021
56b206a
fixed uint24 support comments
TzviRonen Sep 8, 2021
a108eee
t
TzviRonen Sep 8, 2021
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2 changes: 1 addition & 1 deletion canopen/pdo/base.py
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Original file line number Diff line number Diff line change
Expand Up @@ -562,7 +562,7 @@ def get_data(self):
data = data | (~((1 << self.length) - 1))
data = od_struct.pack(data)
else:
data = self.pdo_parent.data[byte_offset:byte_offset + len(self.od) // 8]
data = self.pdo_parent.data[byte_offset:byte_offset + self.length // 8]
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Using the cached value here seems like a good idea, but it does change the semantics. That should at least be explained in the commit message.

Why not apply the same treatment in set_data()? Is there maybe some intentional reason len(self.od) and self.length are both used in these functions?

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I couldn't think of any reason len (self. OD) is used here.
Somehow len (self.od) changed during the program execution and wasn't equal to self.length when get_data was called. It made the returned data to be in the wrong size. Changing it to self.length fixed the problem.

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Well, len(self.od) returns the number of bits (rounded up to full bytes) that the object consists of according to the node's object dictionary, which is constant. While self.length starts off with the same value, it might be overridden when adding the Variable to a PDO mapping, where you can e.g. specify to map only (the lower) 16 bits of a 32 bit unsigned object. That difference is adjusted in pdo.Map.add_variable().

I agree there are some corner cases in the code that don't deal well with mapping only some bits of an object. But to fix that properly, each use within get_data() and set_data() should be reconsidered individually. Just changing one instance might fix your problem, but cause issues for other users.

By the way, my (hacky) solution so far was to adjust the ObjectDictionary instance to artificially overwrite the data_type member when using partial objects in PDO mappings. That breaks SDO access though, and doesn't cope well with signed numbers (two's complement requires changing the higher bytes as well when crossing zero).

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@acolomb This one


return data

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