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Is there any restriction for canopen cables lengths connected to CANTAP (VW3CANTAP2) ?

Yes. There are certian limits. Canopen architecture is bases on "bus" topology. Any branched derived from the bus are called stubs or stub lines (sometimes just branches). These branches creates reflections when signal goes to and from a device at the end of the branch. Avoid branched as much as possible. Tolerance to certain length in branches depends on canopen speed.
There is a limit of max connection length for one branch.
There is a limit for total lenght of branched per one canopen tap (sum of branches lengths connected to one tap)
There is certain min distance L between two Canopen taps, depending on the lentgh of branches. L > 60% of sum of all branches in a TAP.
Folowing table show the limits of canopen legnt per one branch, total length per tap and min distance betwen taps and total sum (sum of all branches in whole canopen network)

Example:
bus speed is 500kb/s
Max branch length can be 5m, (total max 10m per one TAP)

Lets say that there are 2 taps: Tap1 and Tap2
Lets say than distances between Nodes and Taps are:
Node1-Tap1 = 1m
Node2-Tap1=3m
Node3-Tap2=0.3m
Node4-Tap2=1m
min TAP distance between Tap1 and Tap2 is then L > 60% * max (sum per tap1 , sum per tap2) = 0.6 * max (1m+3m , 0.3m +1m) = 0.6 * 4m = 2.4m
Distnace between Tap1 and Tap2 must be at least 2.4m
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