HeidenhainUltra-High-Accuracy Incremental Angle Encoder, 36000 Lines/Rev, 11 µApp Sinusoidal Output, Integral Bearing with Separate Shaft Coupling, Measuring Steps to 0.00005°

Product Description

What this part is

This is a HEIDENHAIN ROD 800 incremental angle encoder with 36000 lines per revolution, HEIDENHAIN ID number 219 845-21. It is a large-diameter, ultra-high-accuracy angle encoder with an integral bearing, designed for connection to the measured shaft through a separate shaft coupling.

HEIDENHAIN reserves the term angle encoder for devices in the arc-second accuracy class, used on rotary tables, swivel heads, telescope and antenna mounts, printing-cylinder registration and precision indexing. A general-purpose rotary encoder counts revolutions and fractions of them; this instrument measures an angle. It is an incremental device, so absolute angular position is known after traversing the reference mark.

Decoding the designation

ROD is HEIDENHAIN’s designation for a rotary/angular encoder with its own integral bearing, driven through an external coupling. The RON and RPN families share that architecture, while the bearingless ERO and ERA ring encoders are mounted directly on the customer’s own bearing. 800 identifies the ROD 800 family, the large-diameter, highest-accuracy tier in HEIDENHAIN’s sealed integral-bearing angle encoder range. 36000 is the line count: 36000 signal periods per revolution. At 36000 periods per turn, one signal period spans 36 arc seconds, and interpolating that period in the downstream electronics yields measuring steps down to 0.00005°. 219 845-21 is the HEIDENHAIN ID number, the definitive identifier for the exact build, also written 219845-21 and 21984521.

Output signal standard

This encoder delivers 11 µA peak-to-peak sinusoidal current signals, not TTL square waves and not 1 Vpp voltage signals. The 11 µApp interface is HEIDENHAIN’s older analogue current-signal standard, used by legacy HEIDENHAIN counters, position display units and CNC controls of that generation. A control expecting 1 Vpp or TTL will not read this encoder directly; an 11 µApp input or a HEIDENHAIN interface converter is required. The analogue sinusoidal output is what makes the fine interpolation possible, since 0.00005° steps are obtained by subdividing a clean sine pair rather than a square wave.

Published specifications

Type: incremental angle encoder, integral bearing, separate shaft coupling. Line count: 36000 signal periods per revolution, one period equal to 36 arc seconds. Output: 11 µApp sinusoidal current signals, incremental with reference mark. Measuring step: to 0.00005° with appropriate interpolating electronics. Accuracy class: ultra-high accuracy, HEIDENHAIN’s large-diameter angle encoder tier. HEIDENHAIN ID: 219 845-21.

What these specs mean in practice

The coupling is part of the measurement rather than an accessory. A ROD-series encoder has its own bearing, so it is connected through a compliant shaft coupling; the coupling absorbs axial and radial misalignment that would otherwise load the encoder’s bearing and inject angular error into the measurement. A ROD 800 bolted up rigidly to a slightly eccentric shaft produces readings that are precise and wrong.

Signal cleanliness forms part of the accuracy budget. At 11 µApp the signal levels are small, so cable length, screening and grounding are specification items. A single continuous screened HEIDENHAIN cable, free of splices and routed away from ducts carrying motor or contactor wiring, is what the interface documentation calls for.

Quantity and configuration

Sold as one encoder. No shaft coupling, no mounting flange, adapter or clamping ring, no encoder cable or mating connector, no interface box or signal converter, no counter or position display unit, and no manual are included. On this class of instrument the coupling and the cable are specified per installation.

Interchange guidance

Searched as ROD 800 36000, ROD-800-36000, ROD800-36000, ROD800 36000, 219 845-21, 219845-21, 21984521 and Heidenhain angle encoder 36000. ROD 780 and ROD 880 are the current integral-bearing incremental angle encoders in the same architecture, and ROD 880C-36000 carries the same 36000-line count in the current family. Those are carried as cross-references because they share the search intent and the measuring principle, while the mechanical interface and the output signal standard differ: the current families are supplied with 1 Vpp and TTL options rather than 11 µApp. Also in the HEIDENHAIN angle-encoder range are the RON and RPN integral-bearing encoders and the ERO, ERA and RCN families. HEIDENHAIN is the correct manufacturer for a ROD designation, and the ID-number format 219 845-21 is HEIDENHAIN’s own convention.