E-6
ADAM-5510/P31
RS-485 Network
E.2 Line Termination
Each discontinuity in impedance causes reflections and distortion.
When a impedance discontinuity occurs in the transmission line the
immediate effect is signal reflection. This will lead to signal distortion.
Specially at line ends this mismatch causes problems. To eliminate this
discontinuity, terminate the line with a resistor.
Figure E-4:
Signal distortion
The value of the resistor should be a close as possible to the charac-
teristic impedance of the line. Although receiver devices add some
resistance to the whole of the transmission line, normally it is sufficient
to the resistor impedance should equal the characteristic impedance of
the line.
Example:
Each input of the receivers has a nominal input impedance of 18 k
Ω
feeding into a diode transistor- resistor biasing network that is
equivalent to an 18 k
Ω
input resistor tied to a common mode voltage of
2.4 V. It is this configuration which provides the large common range of
the receiver required for RS-485 systems! (See Figure E-5 below).
Summary of Contents for ADAM-5510/P31
Page 17: ...0 Quick Start...
Page 38: ...0 22 ADAM 5510 P31 Quick Start...
Page 39: ...1 Introduction...
Page 43: ...2 Installation Guidelines...
Page 52: ...2 10 ADAM 5510 P31 Installation Guideline Figure 2 10 ADAM 5510 P31 network address DIP switch...
Page 58: ...2 16 ADAM 5510 P31 Installation Guideline...
Page 59: ...3 System Specifications...
Page 65: ...4 I O Modules...
Page 116: ...4 52 ADAM 5510 P31 I O Modules...
Page 117: ...ADAM 5510 P31 5 1 Chapter 5 5 Troubleshooting...
Page 129: ...ADAM 5510 P31 A 1 Appendix A A Quick Start Example...
Page 132: ...A 4 ADAM 5510 P31 Quick Start Example...
Page 133: ...ADAM 5510 P31 B 1 Appendix B B COM Port Register Structure...
Page 137: ...ADAM 5510 P31 C 1 Appendix C C Data Formats and I O Ranges...
Page 147: ...D Performance...
Page 173: ...E RS 485 Network...
Page 181: ...ADAM 5510 P31 F 1 Appendix F F ADAM 4000 5000 System Grounding Installation...
Page 187: ...ADAM 5510 P31 G 1 Appendix G G Grounding Reference...