We have a joystick controller that is capable of controlling PTZ, DVR and Matrix Switch. When controlling the PTZ, it is also controlling the 5 DVRs sequentially, from DVR number 1 to DVR number 5 in about 20 second intervals. It is unable to control either PTZ or DVR alone. Could the problem be a result of faulty wiring? 
  
Controller (3-Axis Joystick Keyboard) 
Transmission signal RS-485 
Signal Transmission Cables CAT6 
5 Standalone DVRs 
  
Any help would be greatly appreciated. Apologies for the poor English. It is not my native language.