Resolver vs encoder: which feedback to order
If the motor runs hot, oily, or under shock, the feedback is often a resolver — not an optical encoder. Resolvers (Tamagawa TS2620 / TS2640 and similar) are analog; the drive must be built for them. Photograph the unit. Do not “upgrade” to an encoder unless the drive supports it.
Request a quoteHow to tell resolver from encoder
- 1
Read the type stamp
TS26xx-style numbers, “resolver,” or R/D markings point to a resolver. TS52xx, EQN/ERN, SKM, DFS, A860 point to an encoder or pulsecoder.
- 2
Count wires and look at the drive
Resolvers typically use sine/cosine / excitation analog pairs. If the servo amplifier only has an encoder port (TTL, EnDat, serial), it is not a resolver drive.
- 3
Match pole count and transformation ratio
A “same size” resolver with a different pole count will not commutate. Copy the full Tamagawa or OEM string, not just the diameter.
- 4
Send motor and drive plates together
Many resolvers are sold as motor spares. We quote the resolver when it is separate; otherwise the motor.
When a resolver is the right spare
Steel, paper, foundry, and outdoor axes abuse optics. The resolver survives temperature and vibration the encoder will not. Replacing it with an optical encoder means a drive and cable change — a project, not a spare.
When you actually have an encoder
If the plate says incremental, EnDat, or Fanuc A860, order that encoder / pulsecoder. A resolver will not plug into those ports.
Resolver vs encoder FAQ
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