Due to EtherCAT limitation, up to 4 counters per SIRIUSe device can be used at the same time.

Four counters can be used at the maximum sample rate of 10 kHz

Only two counters can be used at 20 kHz sample rate. 

In both cases, it is not recommendable to use multiple SIRIUSe slices with counter on the same EtherCAT chain. 

The limitation is the same for the SIRIUSe-HS slice, even though the device have a higher possible sample rate. When the counter is connected to the device, the device is behaving just like a normal EtherCAT (not HS) device.