Siemens 8SX8503-0AB00 Bus Terminal | PROFIBUS Termination

This bus terminal provides a physical connection point for PROFIBUS networks. It terminates the bus line with the correct 220-ohm resistor network. You can install this terminal at the start or end of any segment.

Technical Specifications

Parameter	Details
Brand	Siemens
Model	Siemens 8SX8503-0AB00
Category	Bus Terminal (PROFIBUS Accessory)
Dimensions (H x W x D)	75 mm x 25 mm x 45 mm
Weight	0.05 kg
Number of Ports	2 (incoming + outgoing)
Termination Resistors	220 Ω each (3 resistors in series)
Characteristic Impedance	150 Ω to 165 Ω (matching PROFIBUS cable)
Signal Type	RS-485 differential
Data Rate Range	9.6 kbit/s to 12 Mbit/s
Internal Components	3 termination resistors + 1 PCB + 1 plastic housing
Connector Type	9-pin D-sub female (both ports)
Pin Assignment	Pin 3 (B-line), Pin 8 (A-line), Pin 5 (GND)
Termination Enable	Manual switch (ON/OFF)
Bus Biasing	Provides +5V and GND biasing when enabled
Power Supply Requirement	None (passive device)
Built-in Energy Storage	None
Protection Rating	IP20
Operating Temperature	-20°C to 70°C
Mounting Method	DIN rail (35 mm) or screw holes

Detailed Feature Overview

This bus terminal includes a manual termination switch for easy setup. You simply turn the switch ON at both network ends. The internal 220-ohm resistor network matches PROFIBUS cable impedance precisely.

The terminal supports data rates from 9.6 kbit/s up to 12 Mbit/s. Consequently, it works with both older and modern PROFIBUS installations. Two 9-pin D-sub ports allow daisy-chaining through the network.

You will find biasing circuitry inside this active terminal. This biasing pulls the idle bus to a defined high state. Without proper termination, signal reflections cause communication errors.

Installation and Usage

Siemens 8SX8503-0AB00 mounts on a 35 mm DIN rail securely. Connect your PROFIBUS cables to the D-sub ports firmly. Enable termination only at the two physical ends of your network.