Distributing time through RS-485, Master Clocks & GPS Time Server

RS-485 is a balanced differential transmission requiring twisted pair cabling. RS-485 characteristics make it ideal to distribute time data throughout a facility. NetClock ® master clocks and time servers include one or two RS-485 remote output port(s) to provide time through various formats to up to 32 devices at cable lengths up to 4,000 feet. This application note describes RS-485 cable selection, connection and wiring, bus termination requirements, device output details (master clocks and time servers) and device input details (display clocks, time servers, and distribution devices: wireless systems and signal converters).

Device Type	Device	Current Models
Output	MasterClock	NetClock 9389/9383
Output	GPS Time Server	NetClock 9389/9383
Input	RS-232 Converter	TimeTap 8179T
Input	Wireless Distribution	TimeBurst 8185
Input/Output	Display Clock	TimeView TV230/400
Input/Output	Ethernet Time Server	9388
Table: RS-485 Devices for Time Distribution

RS-485 Topics:

• Cable selection
• Connection and wiring
• Bus termination
• Device outputs
• Device inputs
• Troubleshooting