Road Unit

The logical loop occupancy information is reported via a digital port from the loop detector to the MD-440 slave board, whereas the analog loop detuning signal is transmitted via the RS-485 connection. By this it remains possible to connect alternate presence detectors (at the expense of having no loop detuning information any more). The slave board passes this information to the master via one digital port and the I2C bus. It also services the angled axle sensors if present and reports their activation signals via the two remaining ports. Thus, together with the signals of the long axle sensors which the master board is servicing itself, it receives all informations necessary to classify vehicles passing the sensor setup.

All processing components are field-programmable and their programming interfaces are easily accessible, so on-site reprogramming does not impose any difficulties.




The CLASSAX interface which must be installed in whatever "road unit" at the AVC site comprises the electronic components necessary to operate the sensor setup. There is first a FEIG M4D detector servicing the inductive loop. Next there is a SENSOR LINE MD-440 assembly consisting of two specially modified MD-220 dual opto-electronic interfaces which are joined together in a master-slave configuration and operate the axle sensors. If the interface is to be powered with 110...220 VAC it also incorporates a suitable power adapter which can be omitted when a 12...24 VDC supply is available.

These components are mounted and pre-wired on a common DIN rail. The customer is free to mount this rail in a containment of his choice or remove the components and put them on a rail inside of his own assembly. Having done this connecting the sensors, power supply and host computer data link is a matter of seconds.

The actual vehicle classification software is running on the MD-440 master board. It is connected to the slave board with three digital ports and an I2C bus interface. The slave board in turn is connected with a digital port and a RS-485 serial interface to the loop detector.




The MD-440 master board has an RS-232 interface and offers various output modes for signal analysis, debugging and output of vehicle data and classification results.