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Interfacing RIEGL Laser Instruments with a PC


How to Acquire Rangefinder Data with a Standard PC

A standard PC is usually equipped with 2 serial ports (to connect mice, modems, etc.) and at least one parallel port for connecting, e.g., a printer. Serial ports are basically bidirectional in order to acquire data from, e.g., a modem, whereas the parallel port was originally intended for data output only.

Furthermore, a wide variety of interfaces exists relying on data input via the PC bus system. They all require specific plug-in cards to provide access to the bus system (e.g., GPIB IEEE 488, field bus systems). These approaches are not considered in the following.
Serial Interface Ports:

9-pole socket

RIEGL laser instrument are commonly equipped with serial interfaces available as RS232 or RS422 types. The RS232 type interfaces can be directly connected to the PS's serial port using standardised PC interface cables. The major advantage is that this interface is supported by a large number of software products.

However, the maximum transfer speed of the PC's RS232 in limited to 115 kbit/sec. (corresponding to 11.5 kbyte/sec) which is insufficient for some high-speed ranging applications.

 Parallel Interface Ports:

25-pole socket

Parallel interfaces simply cut this limitation in transfer speed by using more than one physical transmission line simultaneously. Nowadays, PC systems are equipped with parallel ports addressed as extended capabilities ports, or enhanced parallel ports, or by the acronyms ECP, EPP, or only enhanced parallel. Data rates (in the ECP mode) can be up to 2 MBytes/sec. Detailed descriptions of these interface can be found in the IEEE standard 1284 - 1994.

All of these interfaces support bi-directional high-speed communication between PC and an external device, e.g., RIEGL laser products for range imaging applications (scanning laser rangefinders) equipped with a parallel data interface.

The interface can be accessed from DOS-based programs as well as from windows-based applications. Windows 95 even provides an built-in driver for ECP, which simplifies application development.

How to Check the PC's Parallel Port

If your PC is equipped with a Pentium type processor and is certified as Win95 compatible, there is a very high probability that it will actually support ECP mode.

Ways to find out:

  1. Start the Control Panel
  2. Clik in icon System
  3. Select the Devices
  4. Click on Connections (COM and LPT), which shows all serial and parallel ports available.
    Check if the parallel port to be checked already shows ECP. If not, then:
  5. Click on the desired parallel port
  6. Click on driver, then other driver and select show all models.
  7. Now select ECP and then click OK (two times), which starts to install the ECP-driver. Now the LPT-Connection should be notified as ECP when checking it as described in point 4.

Information contained herein is believed to be accurate and reliable. However, no responsibility is assumed by RIEGL for its use. Technical data are subject to change without notice.

RIEGL General Information GI008 (3/96)

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Last updated 05/23/02