10.2 Technical Information

10.2 MINISCALE PLUS Technical Information

10.2.1 MINISCALE PLUS Performance Parameters

10.2.2 Dimension Tables, Load Capacities, and Moment Loads for Standard Width MINISCALE PLUS

Standard size 7 and 9

Standard size 12 and 15

10.2.3 Dimension Tables, Load Capacities and Moment Loads for Wider MINISCALE PLUS

Wide size 14 and 18

Wide size 24 and 42

10.2.4 MINISCALE PLUS Components and Working Method

MINISCALE PLUS is an optical incremental measuring system consisting of the MINIRAIL guideway system and the following additional components:

• A Dimensional scale on the guideway
• B Optical sensor on the carriage
• C Flexible sensor printed circuit (must not be subjected to dynamic loads)
• D Interface module

The control cable E with D-Sub 9 connector must be provided by the customer; a flexible cable should be used where necessary.

Various construction types of the interface module are available. These are described in detail in the "Interface module" section.

A Flat Flex Cable (FFC) inserted between the flexible sensor printed circuit and the interface module allows flexible positioning of the interface module. The FFC is suitable for dynamic loads. (See chapter 10.2.8 for details.)

Dimensional scale and optical sensor

The high-precision dimensional scale is part of the hardened guideway surface, with a scale pitch of 100 µm. Two LEDs in the sensor illuminate the dimensional scale. Illuminating different structural areas produces light and dark fields. These optical signals are detected by the sensor and converted into electrical signals. The raw signals from the sensor are processed by the interface module.

The illumination level of the LEDs is actively controlled. This counteracts ageing effects of the system and compensates for contamination on the dimensional scale.

Components of the interface module

Interface module

The raw signals are processed by the interface module and converted into standard output signals. Analog or digital interface modules are available.

Ensure that the ZIF connector F is easily accessible and that the LED indicators (G and H) on the interface module are clearly visible. Unlike the analog interface, the digital interface includes a compensation button I, which must also be easily accessible.

• C Flexible sensor printed circuit
• D Electronics (available in various construction types)
• F ZIF connector
• G Green LED (operating voltage indicator)
• H Red LED (error indicator)
• I Compensation button (digital interface module only)

The following construction types of the interface module are available:

For customers with electronics expertise, digital interface modules can also be assembled and integrated into the customer's own electronics after consultation with SCHNEEBERGER.

Order code: KI

10.2.5 Signal Processing

Further information on signal processing is available in the download area of our website:www.schneeberger.com

Analog output format

Differential sin/cos analog signals with reference pulse, 1 Vpp (at 120 Ω).

The incremental signals sine and cosine are 90° out of phase and correlated with the markings on the encoder scale. One electrical signal period (360°) corresponds precisely to the scale pitch of the dimensional scale, 100 µm.

The reference pulse always marks the same section of the sine and cosine signal paths electronically. Therefore, the intersection of the two signals within the reference pulse marks a precisely defined position on the dimensional scale.

The sine signal either lags behind the cosine signal or appears before it, depending on the direction of motion.

Digital output format

Differential interpolated digital signals with reference pulse (A, B, R) TTL signals (RS422).

The digital interface module both processes the raw signals and interpolates the processed analog signals. Interpolation achieves a resolution of 100 nm.

The digital signal waveform consists of A and B signals. The spacing between the two edges of signals A and B corresponds precisely to a distance of 100 nm. Thus the 100 µm pitch of the encoder scale is divided by interpolation into 1000 segments of 100 nm. The A signal either lags behind the B signal or appears before it, depending on the direction of motion.

The width of the reference pulse is the same as the spacing between the two signal edges of A and B (100 nm).

The edges of the incremental signal and the reference signal are synchronised.

10.2.6 Incremental Track

In the standard version, the incremental track extends over the entire length of the guideway. Position and length can be adapted to customer requirements.

S1 = Start of the incremental track

S2 = Length of the incremental track

Restrictions

• For analog MINISCALE PLUS guideways, S2 must be at least 30 mm.

Reference marks

Incremental measuring systems cannot determine the exact position when switched on. For this reason the reference track is added alongside the incremental track. One or multiple reference points can be marked on the reference track.

Standard version

The following reference position is defined as standard for all sizes:

• Referencing in the centre of the first and second fixing hole

Special versions

Any number of reference marks can be chosen at any position along the reference track. It is necessary for the reference marks to be synchronised with the dimensional scale. Specifically this means that the reference marks can only be placed in multiples of 0.1 mm, since the pitch of the dimensional scale is 0.1 mm. A minimum distance of 1.5 mm between the reference marks should be maintained. Additionally, the distance between the end of the incremental track and the reference mark must be at least 2 mm.

Restrictions

• The attachment holes on guideways of type 7 and 9 are located on the reference track. The reference marks must therefore be placed BETWEEN the attachment holes for both of these sizes.
• When specifying the reference mark(s), ensure they can be seen by the carriage's sensor.

10.2.7 Analog (1VSS) and Digital (TTL) Interface Module Pin Connections

MINISCALE PLUS provides 9-pin D-Sub male connector or solder terminals as interface connection options.

9-pin D-Sub male connector or solder terminals:

10-pin ZIF connector:

10.2.8 Extensions

Extensions can be used when the interface module cannot be mounted directly on the sensor. A Flat Flex Cable (FFC) is used between the sensor printed circuit and the interface module.

Advantages of extensions:

• By relocating the interface module to a non-moving position, the mass of the moving system can be reduced.
• The shielded FFC cable supplied with the extensions is also designed for dynamic loads. The recommended minimum bending radius is 10 mm. In contrast, the flexible sensor printed circuit can only be installed statically.
• FFC cables provide low push force. This can be an advantage where cables used in cable chains are too rigid.
• The FFC cable can also be folded once during installation.

FFC cables are available in three lengths: 250 mm, 400 mm and 600 mm. The extension cables are supplied with adapter plates.

Adapter

Used for the electrical connection between the sensor printed circuit and the extension cable. Two ZIF connectors are provided on the adapter for this purpose.

Clamp Plate

Can be used for strain relief or to guide the FFC cable. Two M3 spacers are mounted on the plate.

Base Plate

Can be used as a base or to clamp cables.

10.2.9 Lubrication

Overview

Lubrication is a design element and must therefore be defined during the development phase of a machine or application. If lubrication is specified only after the design and construction are complete, operational difficulties are likely. A carefully designed lubrication concept is therefore a hallmark of advanced and thoughtful design.

Parameters to consider when choosing a lubricant: