Available in incremental, absolute and commutation models, each encoder incorporates a microcontroller unit (MCU) plus a custom-built ASIC to carry out accurate data capture and processing. The ASIC’s diagnostic capabilities ensure that the encoder continues to run at peak performance, and allows the user to identify potential problems that might arise before they can cause any operational disruption – this is something that other encoder options on the market are not in a position to do.

Figure 2: CUI’s AMT series of capacitive encoders.

AMT series encoders generally draw only 6mA of current even when operating at their highest resolution, whereas an optical encoder solution is likely to be an order of magnitude greater (around 50mA to 80mA) and a magnetic encoder solution even greater still (in the region of 120mA to 150mA). The component parts involved in these encoders are all long-lasting. There are no LEDs to replace, for instance. The encoder will usually outlive the motor itself, so there are no replacement costs to factor in. The longer lifespan and substantially reduced implementation time of these devices means that they present engineers with a significantly reduced cost of ownership compared to alternative solutions. Adaptive sleeves allow AMT encoders to be mounted to various shaft diameters. Consequently, there is no need to keep different encoder models in stock, thereby simplifying inventory management and keeping the associated costs down. Finally, the programmability means that, as well as accelerating the production process back in the factory, fine-tuning can be done when the encoder is in-situ.
 

Encoder Type Capacitive Encoder Optical Encoder Magnetic Encoder
Accuracy Level High High Low
Dirt/Dust Resilience High Low High
Operational Temperature Range Wide Narrow Narrow
Power Consumption Low (6mA) Medium (>50mA) High (>120mA)
Programmability Yes No No
EMC Immunity High High High
Magnetic Immunity High High Low
Resolution Range Wide Wide Narrow

 
 Table 1: Comparison of different encoder technologies.