Error code U7 Daikin VRV3 (troubleshooting)

Brand : Daikin VRV 3 Model : RXQ14PAY13 error code : U7 Description of Fault Outdoor Unit Communication Error to Slave CU Detail of Fault This is a Communication problem between the Outdoor unit&in a multi module system. This can caused if one of the slave Outdoor unit&has been turned off,or if the Outdoor PCB has been set to look for a heat/cool changeover master.Apply power to the unit that has lost power. Change the heat/cool changeover setting back to master. remember to disconnect the (X1A)clip, PCB power supply incoming clip after ermergency setting. if not the error come U7 will happen again.