Optical absolute encoder
Pepperl+Fuchs AVM78E / CVM78E flameproof optical absolute encoder
78 mm flameproof absolute encoders for Zone 1/2 and 21/22 hazardous areas and mining, with 16-bit single-turn and 14-bit multi-turn resolution over SSI, CANopen, PROFIBUS or DeviceNet; IP66, -40 to +70 °C.
Key specifications
| Speed (max) | 3,000 rpm |
|---|---|
| Ingress protection | IP66 |
| Temperature | -40–70 °C |
| Data / bus | SSI, CANopen, PROFIBUS, DeviceNet |
| Resolution (max) | 30 bit |
| Resolution | 16 bit single-turn + 14 bit multi-turn |
| Approvals | Ex db (Zones 1/2), Ex tb (Zones 21/22), Ex I M2 (mining), Ex-NEPSI |
| Housing | 78 |
Summarised in our own words from Pepperl+Fuchs SE (family-owned)'s published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Figures listed in the overview under the DVS78E data with AVM78E/CVM78E as order codes. Sensing principle not stated; classed optical-absolute (assumption).
Specify Motion is not affiliated with Pepperl+Fuchs SE (family-owned). Pepperl+Fuchs and AVM78E / CVM78E flameproof are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
Alternatives that meet or exceed these figures
Engineers often come to us with a Pepperl+Fuchs part number and leave with an alternative that is easier to source, quicker to deliver or a better fit for the machine. These series from our supply network is the closest match on published figures.
Multi-turn absolute hollow-shaft capacitive encoder that holds position through power loss, so no re-homing.
| Published maximum | AVM78E / CVM78E flameproof | VLM |
|---|---|---|
| Resolution | 30 bit | 32 bit meets or exceeds |
Figures are the highest published for each series and are not always measured the same way. A higher figure is not automatically a better choice: mounting, duty cycle, feedback, connectors and approvals matter too. An engineer will check the fit against your application before recommending anything.
What an optical absolute encoder is
An optical absolute encoder reads a unique code pattern on a disc or scale, so every position has its own digital value and position is known immediately at power-up. Single-turn encoders give position within one revolution; multi-turn encoders also count revolutions using gears or electronic counters. Position is sent over a serial interface such as SSI or BiSS, a manufacturer-specific protocol, or a fieldbus. Optical scanning gives high resolution, typically 17 bits per revolution or more in servo encoders, and good accuracy.
When engineers choose an optical absolute encoder
Choose an optical absolute encoder where knowing position at power-up matters, such as robots, machine tools, multi-axis machines and axes that cannot be homed safely. It removes homing routines and supports safety functions. The trade-offs are cost, interface compatibility and contamination sensitivity. Battery-backed multi-turn types need battery maintenance; gear or energy-harvesting types avoid that. In very dirty environments, magnetic or inductive absolute encoders may suit better.
How to specify the Pepperl+Fuchs AVM78E / CVM78E flameproof
Send these with your enquiry and an engineer can confirm the right AVM78E / CVM78E flameproof variant or an equivalent:
- Single-turn resolution (bits)
- Multi-turn range (revolutions)
- Interface: SSI, BiSS, proprietary serial or fieldbus
- Accuracy (arcsec)
- Shaft or hollow shaft size (mm)
- Speed (rpm)
- Environment and safety rating
Common mistakes to avoid
- Choosing an interface the drive does not support
- Forgetting battery maintenance on battery-backed multi-turn types
- Confusing resolution with accuracy
- Ignoring cable length limits for serial interfaces
Pepperl+Fuchs AVM78E / CVM78E flameproof: frequently asked questions
What is the Pepperl+Fuchs AVM78E / CVM78E flameproof?
78 mm flameproof absolute encoders for Zone 1/2 and 21/22 hazardous areas and mining, with 16-bit single-turn and 14-bit multi-turn resolution over SSI, CANopen, PROFIBUS or DeviceNet; IP66, -40 to +70 °C. Published series figures include speed 3,000 rpm, temperature -40 °C, temperature 70 °C, resolution 30 bit. It is made by Pepperl+Fuchs SE (family-owned); Specify Motion can help source it or propose an equivalent.
Who makes the Pepperl+Fuchs AVM78E / CVM78E flameproof?
The Pepperl+Fuchs AVM78E / CVM78E flameproof is made by Pepperl+Fuchs (Pepperl+Fuchs SE (family-owned)) and is listed here for engineers comparing options. Specify Motion is not affiliated with Pepperl+Fuchs SE (family-owned); brand names are used only to identify the product.
What is the speed of the Pepperl+Fuchs AVM78E / CVM78E flameproof?
The published series maximum speed is 3,000 rpm. Individual models and sizes in the AVM78E / CVM78E flameproof range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Pepperl+Fuchs AVM78E / CVM78E flameproof?
Yes. On published figures, Netzer Precision VLM is the closest match from our supply network. An engineer confirms the fit against your application before recommending anything.
What is the difference between single-turn and multi-turn absolute encoders?
A single-turn absolute encoder knows its angle within one revolution. A multi-turn absolute encoder also counts complete revolutions, so it knows total position over many turns even after power loss. Multi-turn encoders avoid homing on axes driven through screws or gears.
Which interface should an absolute encoder use?
Use the interface supported by the drive or controller. SSI is simple and widely supported, BiSS-C is an open bidirectional protocol, and several manufacturer-specific protocols are common on machine tools and servo drives. Fieldbus encoders suit PLC networks. Check cable lengths and update rates for the control loop.
Further reading: Absolute vs incremental encoders · How to select an encoder · Encoders and feedback
Other optical absolute encoder series
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