ICP DAS USA 7000 user manual Gnd

For example, the ￿7510, ￿7510, ￿7510 are used to isolate local modules from ￿RS-485 network. If there is high energy transient on ￿RS-485 network, all the local modules will be safe.

Isolation Configuration (Strongly Recommended)
Host	R	RS232	7520	￿RS-485		RS485	￿7510	￿RS-485
	T		D+				D+
PC			D-				D-
		RS485
PLC						RS485
	GND			7xxx				7xxx
	Is terminator
		￿7510		￿7510		￿7510
			RS485		RS485		RS485
		￿Group A		￿Group B		￿Group C
			RS485		RS485		RS485
		7xxx		7xxx		7xxx
		7xxx		7xxx		7xxx

If the RS-485 network is not over 100 meters, the terminated resistors are not needed. However, it may be necessary to insert two terminated resistors at both end of the RS-485 segment. It is not easy to calculate the value of a terminator resistor. The best way to do this is to use an oscilloscope to check the RS-485 signal directly. If the impedance match of RS-485 network is OK, the oscilloscope will show a very nice square wave. If these square wave signals are distorted, the user will need to insert two terminators at both end of the RS-485 segment.

OK	Resistor	value	of	Resistor value of
	terminator is too small			terminator is too big

7000 Bus Converter User Manual (version 1.2,Feb/2003, 7PH-006-10) --------------- 75