Question:
How to avoid the synchronization error of Simotion D435 and CX32?

Answer:
Possible reason: The current controller sampling time is different between the setting in infeed and in motor-module or in CX32. Another reason is the setting of Ti/To is not correct. For example, If an infeed is connected to the Sinamics-Integrated or CX32 in chassis type, the current sampling time will be adjust to 375 µs automatically (depending on Power >=500kW). Each additional motor-module (vector control) increases 125 µs the current sampling time. With three vector modules it is not possible to set the sampling time less than 375 µs and with four vector modules the minimum sampling time is 500 µs.

Solution:
If an Infeed in typ of chassis (HX) is connected to Sinamics-Integrated or the number of vector module in the CUs (Sinamics Integrated and CX32) are different, you have to adjust the current sampling time in the drives manually or you choose another configuration.

If an infeed (type chassis >=500kW) is connected to a CU-Integrated/CX32, the current control sampling time is fixed to 375 µs. If the number of drives is <= 3, the sampling time of drives can be adjusted manually to 375 µs. If more than 3 vector modules are connected to the CU, it would be a problem. You can avoid this problem by connecting the Infeed to a separate CU320. Then the current sampling time for the vector modules is adjustable without consideration of Infeed.

In case of sampling time modification you have to keep to following rules:

• Ti and To must be a whole-numbered of the current sampling time (p115 [0]).
• The speed-controller sampling time must be a whole-numbered of the current sampling time;
• Tdp > Ti+To; Ti<=To; Tdx < To; Tmapc>=Tdp;

Definition:

• Ti: actual value acquisition [ms]; -To: setpoint acceptance [ms]
• Tdx: Data_Exchange_Time .; - Tmapc: Master application cycle [ms]
• Tdp: DPcycle [ms]

Minimum current sampling time:
1 Vector = 250µs, 2 Vector 250µs , 3 Vector 375µs, 4 Vector 500 µs; Changing sampling times is located at HW-Config. under Isochronous Operation.

Example:
 If 3 vector modules are connected to one CU, then the current sampling time can’t be lower than 375 µs.

• Ti will set to 375 µs and complies the rule of whole-numbered of the current sampling time (current sampling time = Ti x 1).
• To will set to 750 µs to meet To is higher or equal as Ti.
• The DP clock (Tdp) is 3 ms and complies the rule Tdp > Ti + To.
• The speed sampling time must be a whole-numbered of the current sampling time. Now synchronization must be possible.

You can also set Ti = 750 µs and To = 1500 µs and complies the rules for a correct synchronization.

After sampling time modification the drive identification (standstill and if possible running measurement) is necessary.