Question 1

What is the working mechanism of a POSICoder?

Accepted Answer

A POSICoder is a differential transformer integrated on a chip. The copper strips on a scale or disc or the teeth of a gear modulate the coupling between the primary and secondary windings. A more detailed description can be found on the Technology page.

Question 2

Does a POSICoder operate at zero speed?

Accepted Answer

Yes, the sensing principle in a POSIC encoder is a differential transformer. The primary coil generates a magnetic field, the secondary coils measure the magnetic field, which is modulated by the scale or codewheel. This mechanism works perfectly when the codewheel or scale is not moving.

Question 3

What is the maximum speed of a POSICoder?

Accepted Answer

The maximum speed is set by the parameter Max Speed BB as listed in the corresponding table in the Section “Ordering Code” at the end of each datasheet. For linear encoders it may vary from 20 mm/s to 60 m/s and for rotary encoders from 5 to 25'000 RPM.

Question 4

What is the time-delay of the POSICoder output signals?

Accepted Answer

The time-delay depends mainly on the setting of the parameter Max Speed BB as listed in the corresponding table in the Section “Ordering Code” at the end of each datasheet.
For BB = 01 to 09, the delay is the time-constant of a first-order filter with adjustable bandwidth and may vary from 50 us to 25 ms.
For BB = 20 – 23, the position-filter is a second order filter with zero delay at constant speed.

Question 5

Can I make my own scale or disc?

Accepted Answer

Yes! Scales and discs are straightforward PCBs (Printed Circuit Boards) with copper strips on the frontside and a plain copper layer on the backside that acts as a screen against metal objects behind the scale or disc. The PCB consists of 0.6 mm FR-4 (or thicker), 35 um copper and a protective layer (typically solder mask or nickel/gold finish). Detailed information:

Question 6

What is the pitch or period-length of a POSICoder scale?

Accepted Answer

The pitch or period-length is the center-to-center distance between two copper strips. This should be between 1.2 and 1.4 mm and is explained in more detail in the Application Note AN018 
 
.

Question 7

Is a POSICoder REACH and RoHS compliant?

Accepted Answer

Yes, you can download POPSICoder's RoHS and REACH declaration here:

Question 8

Will my Evaluation Kit work with encoders from both POSIC and POSICoder?

Accepted Answer

The hardware in the Evaluation Kit will work with POSICoder and POSIC encoders. However, the software is different. For POSICoder, the POSICoder Software must be used, whereas for POSIC, the ASSIST Software must be used. Both softwares can be installed on the same PC, but only one software can be activated at the same time.

Question 9

Is a POSICoder immune against magnetic fields?

Accepted Answer

The POSIC encoder is a differential transformer. The primary coil generates a high-frequency magnetic field (1 – 2 MHz) and measures this field back using the secondary coils. Perturbations below 1 MHz are filtered out. As most magnetic fields from magnets, motors, drives etc are well below 1 MHz, these magnetic fields do not influence the encoder. In addition, the secondary coils in the encoder are arranged in a differential configuration, so that a magnetic field acting on two differential measurement coils is eliminated.
So yes, POSICoders are immune against magnetic fields.

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