Non-contact measurement of speed and length

Why non-contact measuring?
The optical measuring device VLM500 opens completely new perspectives for quality assurance and automation processes in industry. Lengths and velocity can be measured extremely precisely and free from wear, where traditional, wheel solutions, are either not suited to the process or are not sufficiently precise. With the VLM500 ASTECH offers a measuring device which is mostly compatible with the well-established VLM320 and which has been customized to the requirements of industrial applications.
Independent from the material the VLM500 measures lengths and velocities without contact and due to its comprehensive interfaces it can optimally be integrated into automation and quality assurance processes in different industrial sectors.


The VLM500 works optically and contact-free. Based on a CCD sensor it implements the spatial filter principle. Spatial filter is the generic term for a measuring principle for the optical determination of velocity and length of moving objects.

The spatial filter is based on the filtering effect of lattice-like structures (grid modulation). Basically, the functional principle of the VLM500 can be described as follows: The measuring object is projected on the CCD sensor which functions as an optical grid (no image taking). The VLM500 is equipped with an LED light source for the illumination of the measuring object. Due to the grid modulation a signal frequency, which is proportional to the speed, occurs upon movement of the object. The device calculates the velocity from the measured signal frequency. Several control circuits allow for automatic adjustment to most diverse materials.

The VLM500 does not put high requirements on the surface character of the measuring object: Precise measurement is facilitated on periodic structures as well as on stochastic surfaces of metals, wood, rubber or paper.


  • Contactless
  • Measuring range up to 50 m/s
  • Measuring uncertainty ±0.025 %
  • Working distances: 185 mm, 240 mm or 330 mm (and customized)
  • Slip-free
  • Wear-free
  • Material independent
  • High power illumination LED
  • No dangerous laser radiation
  • Robust and precise
  • Insensitive to contamination
  • Economical
  • Various interfaces
  • Easy installation
  • Easy maintenance
  • PC software for parameterization
  • 60-months warranty
  • Quality product made in Germany


Robust and precise
The robust construction of the VLM500 facilitates its use in harsh industrial environments and allows slip-free measurement of speed and length in a wide range of production processes, achieving high measuring dynamics and accuracy.

Low maintenance
Due to the contact-free measuring principle the VLM500 does not only work more precisely than other systems that are subject to slip, but also without wear through friction, which minimizes the need for servicing. Damage or impurity of the surface to be measured does not occur.

Flexible and versatile
The VLM500 works autonomously. Sensor, illumination, signal processing and power supply have been integrated into the unit. The comprehensive parameterization provides the user with a wide range of functionalities which ensure flexible operation. Among others, acquisition and output times, sliding averaging or scaling of speed and length outputs can be parameterized. All devices are bus compatible (RS232, RS422/RS485, USB, Profibus, Profinet, EtherNet/IP, TCP/IP) and can be synchronized. Via its interfaces the VLM500 can easily be integrated into existing processes, controls or into process data acquisition. It is easy to set up and parameterize (The software "VLMTool" is provided for free).

Quality product
The high quality standard is expressed by a considerably longer period of warranty. Since the 1st march 2014 the warranty period for all devices of the VLM series has been extended to 60 months.

Standard scope of delivery as a set
Due to the complete delivery contents the VLM500 is quickly deployable:
  • Measuring device VLM500
  • Printed manual in German or English
  • USB stick with documentation in German and English and software tool VLMTool (for Microsoft® Windows) for configuration
  • power supply cable, connection cable
  • Alignment tool for the working distance
  • Parameter list and wiring plan

Selectable interfaces
A wide range of applications can be covered with selectable interfaces or the signal in- and outputs:

  • Up to two programming interfaces (RS232, USB, RS422/485)
  • Pulse output with two phases A and B (resolution 8 ns):
    • IPPL (12 V ... 24 V passive, max. 25 kHz)
    • IP5V (5 V active, max. 4 MHz)
    • IPPP (24 V active, max. 4 MHz)
  • In- and outputs (IOPL):
    • ERROR output (extensive self-diagnosis of the device)
    • STATUS output (programmable)
    • TRIGGER 1 input
    • STANDBY, TRIGGER 2 input
    • DIRECTION input
  • Profibus connection
  • Profinet connection
  • EtherNet/IP connection
  • Analogue output cards:
    • IA00 (0 mA ... 20 mA)
    • IA40 (4 mA ... 20 mA)
    • IA04 (0 mA ... 24 mA)

High-performance options and accessories
Several options and accessories provide more possible applications and benefits when using the VLM500:

  • Automatic direction detection
  • Light barrier controller
  • ACM - Analog display unit
  • Counter/Display (PAXICA)
  • Mounting plates
  • Linear alignment units
  • Protective and cooler case

Technical data

Nominal distance1) max. 330 mm
Working range max. ±30 mm
Measuring range 0.08 m/min ... 3000 m/min
Measuring uncertainty2) < 0.025 % in nominal distance
Reproducibility2) < 0.025 %
Averaging-/Update-Time > 0.2 ms with additional 1 ... 32 times sliding average
Length measuring range Internal length range up to 2,000,000 km
Detector / principle CCD sensor / spatial filter with semiconductor grid as reference
Illumination White light LED (expected life span: > 5 years 3))
State indicator
(LED in cover plate)
Sginal (green), Error signal (red), Communication (yellow), Forward (Green), Backward (green)
Power supply, consumption 24 VDC, max. 25 W
Temperature range 0 °C ... 50 °C
Protection class IP 65
EMC Industrial standard in compliance with CE
Weight, Housing dimensions approx. 3.3 kg, 260 mm x 160 mm x 90 mm (without connections)
Programming interface
(max. 2)
for parameter setting, data output and firmware update:
USB (IUSB), RS-232 (I232), RS-422/RS-485 (I4UN), isolated
Opto-isolated outputs4) 2x (Error, Signal status)
Opto-isolated inputs5) 3x (External trigger signal, Idle mode / Lock6),
Definition of the direction of the movement)
Pulse output (Encoder) A/B, 2 phases 90°, Resolution 8 ns, 0.2 Hz ... 25 kHz
Optionally as Open Collector (IPPL), 5V TTL (IP5V) 7)
or Push Pull (IPPP) 7)
Analog output Current output, adjustable as 0 ... 20 mA, 0 ... 24mA, 4 ... 20 mA (IAUN)
Fieldbus interface Profibus (IFBP), Profinet (IFPN), EtherNet/IP (IFEI), Telnet (IFFE),
Standard scope of delivery VLM500, Programming interface on customer request, Power supply cable, Connection cable, positioning aid, USB stick with documentation and software, printed manual

1 Larger working ranges can be offered according to customer demands
2 DIN 1319 / ISO 3534, of measured length, test conditions: measuring length 10 m, active tracking, constant conditions in: temperature (20 °C), distance, velocity, illumination
3 Simple replacement by user.
4 OpenCollector interface card (IOPL). Connections are isolated and short circuit proof.
5 Opto-isolated, short circuit proof, max. voltage 50 VDC, 36 VAC.
6 The idle mode input can be used as a second trigger input. From firmware version 1.10 and higher
7 IP5V and IPPP provide output frequencies up to 4 MHz.


Mr. Jörg Boddien

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