HeidenhainRON-255C-18000-02S09-04Incremental Angle Encoder, 18000 Lines/Rev, 20 mm Hollow Through Shaft, Integrated Stator Coupling

Product Description

What this part is

A HEIDENHAIN RON 255 C, ID 331 705-79 — an incremental angle encoder with integral bearing and an integrated stator coupling, graduated at 18000 lines per revolution. An angle encoder is a higher-accuracy class of device than a general-purpose rotary encoder: it is built for rotary-axis and rotary-table position measurement, where arc-second accuracy matters. The RON 255 resolves to measuring steps of about 0.0005° with suitable interpolating electronics.

Decoding the order code

RON — HEIDENHAIN incremental angle encoder with integral bearing255 — the compact 255 model with a hollow through shaft and integrated stator couplingC — accuracy / model variant designation as marked on this unit18000 — graduation: 18000 lines (signal periods) per revolution02S09-04 — HEIDENHAIN configuration / cable and connection variant code331 705-79 — HEIDENHAIN ID number for this exact build; also written 331705-79

Published specifications

Type: incremental angle encoder, integral bearing, integrated stator couplingGraduation: 18000 lines per revolutionMeasuring step: to approx. 0.0005° with interpolationShaft: hollow through shaft, 20 mm diameter, axial clampingMounting: rectangular flange with 85 mm centring collarElectrical connection: M23 male connector interface (the mating cable connector is not fitted — see below)Origin: Germany (HEIDENHAIN nameplate)

What these specs mean in practice

The integrated stator coupling is the reason to choose a RON: HEIDENHAIN’s stated system accuracy for these encoders already includes the error of the shaft coupling, so you get the specified accuracy at the axis rather than having to budget separately for a coupling you fit yourself. That also means the mounting matters — the 85 mm centring collar and the axial clamp on the 20 mm hollow shaft have to be used as designed, or the accuracy figure no longer applies.

18000 lines per revolution is an incremental count, not an absolute position. The encoder outputs incremental signals plus a reference mark: the control has to traverse the reference mark on power-up before it knows absolute angle. If your application needs position immediately at switch-on, an absolute encoder is the right class of part.

Installation and setup notes

Mount to the 85 mm centring collar and clamp the hollow shaft axially per HEIDENHAIN’s instruction sheet; the accuracy specification depends on it. Match the interface to your control’s expected input before ordering — RON encoders were supplied with different signal interfaces, and the counter or CNC input must be the matching type. Handle the graduated disc assembly carefully; shock loading a glass angle encoder is the usual cause of a dead unit.

What is not included

Encoder body only. The mating connector is not fitted and no connecting or adapter cable is supplied. Also not included: mounting clamps or bolts beyond what is fitted, coupling or shaft adapter, interpolation or counter electronics, EIB/IK interface boxes, HEIDENHAIN diagnostic adapter, alignment tooling and documentation.

Quantity and configuration

Sold as one encoder.

Interchange guidance

RON 255 C, RON255C and RON-255C-18000-02S09-04 refer to this unit; ID 331 705-79 is the definitive identifier and is the number to quote. Other RON 255 builds share the model name but differ in line count, accuracy grade and interface, so a plain “RON 255” is not automatically a substitute — match the line count and the ID number. RON 200, RON 700 and RON 800 series encoders are different families with different flanges and shafts, and RPN 800 is a different product again.