Service USB classic

Owners of other interfaces than Service USB classic can neglect the following chapter.

Service USB classic



Service USB classic is best for controlling fischertechnik® models. More than thirty models out of six different construction kits are supported by the included RealBasic software. The large assortment of additional software makes it possible to control the interface of nearly every program.


System requirements

A Macintosh with USB and OSX 10.5 to 10.8 is required to operate Service USB plus. An external AC adaptor with current limitation (7-15V max. 1.3A) is necessary when using the digital outputs. Up to 100 Service USBs can be run on a Macintosh.


Scope of delivery

  • Service USB classic (the interface)
  • USB A/B cable
  • CD-ROM with driver and a lot of sample programss
  • OSX-Examples for Runtime Revolution, RealBasic, Apple-Script, FileMaker, RagTime, Xcode (C, C++, Objective-C, Cocoa, Java, AppleScriptStudio), 4th Dimension, MaxMSP, Adobe Director, BlueJ, Scratch, TCP/IP, Numbers and the UNIX-Shell

Furthermore you will find Quicktime-movies about the supported fischertechnik®-models, and a detailed instruction manual.


Recommended accessories

The AC adaptor „Service USB power" used to operate the outputs is recommended for all fischertechnik® models. It is short-circuit-proof, overload and underload protected and ensures safety during use. It is a robust switching power supply and can not be compared to low grade transformer supplies.


fischertechnik® construction kits

The following fischertechnik® construction kits are supported in this version of Service USB classic:

  • Industry Robots II
  • Pneumatic Robots
  • Computing Starter Pack

The following models are supported, but are no longer available:

  • Experimenta Computing by Cornelsen
  • Industry Robots
  • Bionic Robots
  • Trainingsroboter
  • Teach-Robot by Kalms&Muerb

There are sophisticated examples for all these construction kit models in RealBasic.


Hardware description

This is the label on the Service USB classic casing and connection sockets:


Service USB classic

The label on the casing is valid when fischertechnik® models are used with Service USB classic in accordance with fischertechnik® instructions as this is what is contained in the fischertechnik® instruction manual. While in nearly all programming languages the bits of inputs and outputs are numerated from 0 to 7, the inputs and outputs in fischertechnik® instruction manual are numerated from 1 to 8. Special attention should be given to Inputs I1-I8 and O1-O8 which are represented in software as bits 0-7.


Connections and interfaces

Service USB classic has the following connections and interfaces:

  • An USB interface on the right at the back. Power is supplied to Service USB classic mainly via the USB interface. Only the output driver requires an external 9V adaptor as the power required by this is no longer supplied by the USB interface.
  • One jack for the external 9V plug power pack „Service USB power".
  • Connectors for connecting 9V plug power packs with fischertechnik® plug connectors.
  • Emergency stop pushbutton sets all outputs to 0V immediately. Both pushbuttons must be pressed at same time.
  • A green LED „operational" shows that the Macintosh driver has been connected and that the interface is functioning properly. This LED must always be on during use.
  • A green LED „supply voltage" shows that an additional adaptor is connected for the digital outputs
  • Sixteen red LEDs indicate the state of the inputs and outputs.
  • Four red LEDs show the value of the analog inputs. If the value is in the lower range (<10%), the LED is off. In the middle range, the LED is on and just before reaching the end of the range (>90%) the LED is blinking.
  • A RS232 interface at the right rear. This serial interface can send and receive characters up to 19200 baud. It is not possible to control the interface via this interface. The interface serves to connect and control devices with an RS232 interface.
  • 36 Sockets to connect fischertechnik® models at the front edge.


Function of the sockets

The 36 socket connections serve the following function:

Service USB classic

9V 0V - An external adapter is connected here to supply current to the motor outputs. The voltage connected here must not exceed 15V. The adapter must limit the current flowing through it to a maximum of 1.3A. The recommended adapter „Service USB Power" (9V= /12W) guarantees safety during use. This is available as an accessory.

0V - All voltage instructions refer to this connection. It is the 0 volt reference point for all inputs and outputs. It is also known as ground (GND).

5V - There are 5V here which are used for the digital and analog inputs. These 5V outputs together create a total maximum current of 100mA. A built-in fuse which resets itself automatically ensures that this current is not exceeded.

I8 - I1 - These are the digital inputs. An input connected to 0V or an open input means logical 0. An input connected to 5V means logical 1. The keys and switches are usually connected between one of the inputs and the 5V pin. I1 is the lowest bit; I8 is the highest bit. Eight LEDs indicate the current state of the inputs. As the eight bits are always counted from 0-7 in almost all programming languages, the counting system used here is different from that of fischertechnik®, as this goes from 1-8.

AX, AY - These analog inputs measure resistance between 0 and 200kΩ with a resolution of 10 bit (1024 steps). These inputs are optimised for the light and temperature sensors from fischertechnik® construction kits. The resistor/sensor is connected between this and the subjacent 5V jack.

A1, A2 - Analog inputs for measuring voltage between 0V and 10V with a resolution of 10 bit (1024 steps). These inputs are optimised for the colour and distance sensors from fischertechnik® construction kits. The voltage/sensor is connected between this and the subjacent 0V jack.

O8 - O1 - Digital outputs for driving fischertechnik® motors. An external adapter must be connected in order to use these outputs. The outputs are short-circuit-proof and protected against overloading and underloading of up to ±15V. The external adapter required for operation must limit the current to a maximum of 1.3A. The adapter „Service USB power", which is available as an accessory, is recommended. The maximum output current is ±200mA for each output at the same time. Motor speed or light intensity is regulated by turning on pulse width modulation.

RX - This is the RS232 receiving data input in the range of 300-19200 baud. The RX input can also be used as digital input bit 12. An open pin or a voltage greater than +3V means logical 0 and an input voltage below -3V means logical 1. The maximum input voltage at this connector must not exceed ±24V.

TX - This is the RS232 data output in the range of 300-19200 baud. This connector has a voltage level of -9V for signal mark and +9V for signal space.

HSKo - This output indicates whether Service USB plus is ready to receive characters. ( Service USB not ready: -9V; Service USB ready: +9V.) This output can also be used as digital output bit 10. In this case a logical 1 corresponds -9V and a logical 0 corresponds to +9V

HSKi - This input indicates whether the receiver is ready to receive characters. ( Receiver not ready: -3V to -18V; Receiver ready: +3V to +18V. ) A disconnected input means that the receiver is not ready. If the receiver does not have a handshake line, or it is unknown whether the line is connected, this line should be connected to the handshake output. A bridge between pins 7+8 (HSKi+HSKo) means that the serial data are always sent. This input can also be used as digital input bit 8. In this case a voltage greater than -3V or an open input corresponds to logical 0 and a voltage less that -3V corresponds to logical 1.


The serial RS232 interface

The serial interface is meant for transmission of data from 300 to 19200 baud with 8 data bits, 1 stop bit and without parity. Hardware handshake is always used for data transmission. No external power supply unit is required for operation. The electricity supplied by the USB is sufficient for operation.

PIN Function
3 RX (input, RS232 receive data)
4 TX (output, RS232 transmit)
7 HSKi (input, RS232 remote station ready to receive)
8 HSKo (output, RS232 Service USB ready to receive)

Pinout of the 9 pin connector

Service USB classicService USB classic

Sub D 9 connector to view of Service USB classic


Technical information

  • Dimensions: 151mm x 90mm x 31mm (width x depth x height)
  • Weight: 158g
  • Data transfer: USB full speed (12Mb/s)
  • USB current consumption: 100mA
  • External voltage (option): 8 to 15V, current limited to 1.3 A
  • Digital inputs: 8
  • Input level: 0V / 5V
  • Analog inputs: 4
  • Input level: 0 - 10V, 0-200kΩ
  • Input resistance: 4,7kΩ
  • Resolution: 10 bit
  • Digital outputs: 8
  • Output voltage: maximum 15V, typical 9V
  • Output current: ± 200mA
  • Maximum data rate: 2000 values per second for all digital and analog inputs simultaneously
  • Display: 22 LEDs
  • Protection against reverse voltage, overloading and underloading, temperature protected, provided the recommended adapter Service USB power is used.



Schematic diagrams

Service USB classic

Block diagram of Service USB classic



Service USB classic

Circuit diagram of Service USB classic