Rotary Encoders / Incremental Encoders
Incremental rotary encoders convert shaft rotation into A, B and Z pulses that a PLC high-speed counter, servo drive or motion controller can count, giving speed, direction and position. Industrypapa stocks the VoxinTech VXT-E series in 38, 40, 50 and 58 mm housings, 360 to 5000 PPR, with NPN, PNP, totem pole and line driver (RS-422) outputs, all with GST invoice and delivered pan-India.
How an incremental encoder works
A and B channels
Two pulse trains, 90Β° apart. Counting the pulses gives distance or angle; comparing which channel leads gives the direction of rotation.
Z (index) pulse
One pulse per revolution, used as a reference point for homing a machine axis or resetting a counter.
PPR and resolution
PPR is pulses per revolution on each channel. A 1024 PPR encoder read in 4x mode by the controller gives 4096 counts per turn.
Incremental vs absolute
Incremental encoders report movement, so position is lost at power-off and the axis re-homes on start-up. For a position that survives a power cut, see our absolute encoders.
VXT-E encoders in stock
| Model | Housing / shaft | PPR | Output |
|---|---|---|---|
| VXT-E38S06-0360-NPN | 38 mm / 6 mm | 360 | NPN open collector |
| VXT-E40S06-0500-NPN | 40 mm / 6 mm | 500 | NPN open collector |
| VXT-E40S06-1024-NPN | 40 mm / 6 mm | 1024 | NPN open collector |
| VXT-E40S06-1024-PNP | 40 mm / 6 mm | 1024 | PNP |
| VXT-E40S06-1024-L | 40 mm / 6 mm | 1024 | Line driver (RS-422) |
| VXT-E50S08-1000-T | 50 mm / 8 mm | 1000 | Totem pole |
| VXT-E50S08-1024-T | 50 mm / 8 mm | 1024 | Totem pole |
| VXT-E50S08-2500-T | 50 mm / 8 mm | 2500 | Totem pole |
| VXT-E58S06-1024-L | 58 mm / 6 mm | 1024 | Line driver (RS-422) |
| VXT-E58S10-5000-L | 58 mm / 10 mm | 5000 | Line driver (RS-422) |
Reading the VXT-E part number
Take VXT-E50S08-1024-T as an example: E50 is the 50 mm body, S08 the 8 mm shaft, 1024 the pulses per revolution and the last letters the output, where NPN is NPN open collector, PNP is PNP, T is totem pole and L is line driver (RS-422).
All models in this range are IP54 rated and run at speeds up to 6000 rpm (3600 rpm on the 5000 PPR VXT-E58S10-5000-L). Supply voltage and wiring colours are listed on each product page.
Choosing the output type
NPN open collector
For PLC inputs wired for NPN (sinking) sensors.
PNP
For PLC inputs wired for PNP (sourcing) sensors.
Totem pole (push-pull)
Drives the signal both high and low, so it works with both NPN and PNP inputs. A good choice when you are replacing an encoder and are not sure of the input type.
Line driver (RS-422)
Differential A/A-, B/B-, Z/Z- signals that resist noise over long cables. Used with servo drives, CNC controls and motion controllers.
Specifying a rotary encoder
- Resolution (PPR) β higher PPR gives finer position, but check the counter or drive input frequency can keep up.
- Output type β match NPN, PNP, totem pole or line driver to the controller input.
- Housing size β 38, 40, 50 or 58 mm, to fit the mounting space and flange.
- Shaft diameter β 6, 8 or 10 mm, matched to the coupling.
- Maximum speed β shaft rpm times PPR sets the pulse frequency the input must handle.
- Supply voltage β check the controller supply against the encoder rating.
- Cable length β for long runs, line driver output is the safer choice.
- Environment β IP54 suits indoor machines; keep coolant and washdown away.
Frequently asked questions
What is the difference between a rotary encoder and an incremental encoder?
A rotary encoder is any sensor that measures shaft rotation. An incremental encoder is the most common type: it outputs pulses as the shaft turns, rather than an absolute position value.
Which encoder do I need for a PLC high-speed counter?
Match the output to the PLC input: NPN or PNP for sinking or sourcing inputs, or totem pole to work with either. Choose the PPR so the pulse frequency stays within the counter limit.
Can I replace an encoder with a different brand?
Yes, if the housing, shaft, PPR, output type and supply voltage match. Send us the old model number and we will suggest a VXT-E equivalent.
What is the price of a rotary encoder in India?
Prices for the VXT-E range start at Rs 2,299 for the 38 mm 360 PPR model. Current prices are shown on each product, with GST invoice.
Buying rotary encoders in India
Every encoder above ships from Noida with a GST invoice, with delivery across India and to 220+ countries. Not sure which PPR or output you need? Send us your controller model and our engineers will help you choose.
Related ranges: absolute and Datalogic encoders, inductive proximity sensors, photoelectric sensors.
