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
