CANopen bus

i have CANopen bus connected from M258 controller if i connected inverter no (4 inverter ) with 8 panel nodes TM5NCO1 BUS STOP
BUT IF CONNECT ALL PANEL (8) ONLY WORKED OK
AND IF I CONNECTED 4 INVERTER ONLY ON BUS WORKED OK
WHATS REASONS
INVERTER TYPE IS NORD SK200E WITH BUS INTERFACE canopen

Your question is a bit hard to understand and I have no knowledge of the hardware you are using but here are a couple general CANOpen tips

Every Node on the bus need to have a unique Node ID. If 2 or more devices are set to the same Node ID, the communications will not work.

Every Device on the bus needs to be set to the same Baud Rate or the communications will not work.

You should use cable specific for CAN communications. DeviceNET is a specialized version of CAN so DeviceNET cable should be OK as well.

The bus needs to be terminated at either end but NOT in the middle. Some devices have built in termination that is selected with a switch but if not, then you should add a 120 Ohm resistor across CAN_H and CAN_L at the ends of the bus.