Terminator multimode encoder signal filter

The filters remove all types of electrical noise (common and differential mode, dV/dt transients, ground loop generated etc.) in the encoder signal lines as well as the corrupting effects of mechanical noise and vibration (phantom movement, dither etc.). They reconstruct the encoder signals to reflect the correct encoder position and speed signaling. Performance is safeguarded and problems such as: Motion system position drift, Home reference loss, False triggering of the receiving inputs, and Receiving input saturation, latch-up or failure are eliminated. (The subject is treated extensively and in detail in our paper Eliminating Phantom Movement in Encoder Applications).  See also the Frequently Asked Questions page.

Like all other Terminator multimode filters, they are standard, all-in-one, comprehensive products, each device addressing all and any combination of known encoder application issues.  The filters process digital quadrature encoder signals with the following features:

• Dual voltage 115/230 VAC twin isolated supply. The twin supply powers the two internally isolated, input and output, filter sections. It can power the monitored encoder with regulated 5 VDC or unregulated 10 VDC,
• Galvanically isolated input and output stages to interrupt unavoidable system ground loops eliminating related noise as well as protecting the input stage of the driven controller from high voltage transients (the galvanic barrier features 5 V/ns dV/dt immunity),
• Four selectable modes of digital processing:

1. Unfiltered: the outputs are buffered replicas of the inputs,
2. Filtered: the encoder inputs are processed for electronic noise only,
3. Recovered x1: the encoder inputs are processed for electronic noise and analyzed for mechanical position to recover corrupted motion sequences. The outputs are in quadrature format and the mark (or index) channel is processed for electrical noise.
4. Recovered x4: Same as the Recovered x1 mode, but with output resolution quadrupling. The output signals are a clock/direction or an up/down pair at four times the input frequency instead of the quadrature format.

• Test mode. Depending on the chosen mode and sampling frequency, the filter outputs simulate the function of a 1024 ppr encoder,
• Direction reversal. One of the encoder channels can be complemented to effect a direction reversal, thus saving the rewiring/reconnection of the encoder signals,
• Supply, signal and worn/faulty encoder indication. Five LEDs indicate the status of the power supply, the three encoder channels and the presence of out-of-sequence signalling, typically caused by a worn or faulty encoder,
• DIP switch selectable options. All operational parameters and functions are set/reset via DIP switches,
• Selectable sampling frequency. The encoder signals are DSP processed at selectable frequencies to interface to slower equipment or tune out problem noise sources in particularly difficult applications,
• Three types of EIA(RS)422 input termination: standard DC, AC and none, and
• Cast aluminum enclosure of IP65 protection and high noise immunity.

The above all-in-one, multimode approach is justified when considering that in practical applications there is typically more than one mechanism at play eroding encoder performance at any time (see our paper on this or the encoder filter FAQ page). This makes a multimode filter the only effective, efficient, viable and conclusive solution to encoder noise problems.

The EFU5 filters are available in Standard and High speed grades. The speed grade specifies the maximum quadrature input frequency which can be processed. The limit is different for each filter mode:

The filter design is characterized by typical industrial application considerations: minimal cost, standard interfacing, fool-proof installation and operation. Like all our encoder filters, the EFU5 features the following:

• It is wired in-line between the encoder and the processing equipment. This minimizes and simplifies wiring, usually one of the most significant costs in an installation,
• It interfaces in a standard way with the encoder outputs and the processing equipment inputs. This enables installation by a non-specialist as well as widening equipment choice,
• It has no special installation requirements, have small physical dimensions and are transparent in operation, and
• It is readily recyclable and made with lead-free materials for minimal impact to the environment.

You can buy small quantities of the EFU5 model online here.