How to read Heidenhain EQN, ECN, and ERN encoders
Heidenhain rotary encoders are a type string, not a diameter. EQN and ECN are absolute (often EnDat). ERN is incremental (often 1 Vpp or TTL). Photograph the full string on the cover, including the numeric suffix.
Request a quoteHow to decode the Heidenhain string
- 1
Capture the whole type line
Example: EQN 1325.049-2048 or ERN 180. Copy every group after the family letters. The suffix is resolution, not decoration.
- 2
Map the family
ERN / EQI = incremental. EQN / ECN / ECI / EQI mixed families: check the datasheet family — EQN/ECN are typically absolute EnDat. Do not order ERN to replace EQN.
- 3
Photograph the cable and coupling
Stator coupling, hollow shaft vs solid shaft, and the connector (often a specific Heidenhain pinout) have to match. A correct electrical encoder with the wrong hollow-shaft diameter will not mount.
- 4
Send the drive or CNC model
Sinumerik, Heidenhain TNC, or a third-party servo changes which protocol we confirm. Include quantity.
EQN vs ERN in one sentence
If the axis keeps position after power-off, you almost certainly need EQN/ECN (absolute). If it homes every start and the plate says ERN, stay incremental. Mixing them is the most common failed Heidenhain order we see.
Linear scales are a different spare
LS, LC, and similar linear encoders are not rotary EQN/ERN units. Photograph the scale housing and the reader head separately. We quote those as linear encoders, not as rotary replacements.
Heidenhain encoder FAQ
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