Omron CK3M / CK3W Axis & I/O Units
CK3W units expand the CK3M programmable multi-axis controller. This is not a relay family and not a general-purpose I/O bus — these units only fit the CK3M/CK5M platform, so they are only bought by customers already running that controller. The CK3W-AX axis interface handles encoder feedback and motion output; the CK3W-MD digital units handle plain I/O.
Lifecycle status
In production
Omron lists the CK3M and CK3W units with live product pages and no end-of-production entry. The expansion units are part of the current machine-controller platform.
What to fit instead: None required
Key specifications
- CK3W-AX1515N is a 4-axis interface unit with DA output (true DAC), pulse plus direction or phase-differential command, digital quadrature or serial encoder feedback to 10 MHz, NPN, plus 16 inputs and 16 outputs
- CK3W-AX1515P is the PNP counterpart of the same 4-axis unit
- CK3W-MD7110 is a 16 input / 16 output NPN digital unit; CK3W-MD7120 is the PNP version. Dimensions 31.6 x 90 x 80 mm
- CK3W-EXM01 is the expansion Master unit and CK3W-EXS02 the Slave unit, linked by the CK3W-CAX003A 0.3 m expansion cable
- CK3W-PD048 is a positioning unit in the same expansion family
- The CK3M-CPU101, CPU111 and CPU121 heads are the controller CPUs these units expand
How to read a CK3W model number
The prefix says the function class; the trailing letter usually says the output polarity.
| Model | Function | Detail |
|---|---|---|
| CK3W-AX1515N | Axis interface unit, 4 axes | N = NPN; DA output, 16 DI / 16 DO, encoder to 10 MHz |
| CK3W-AX1515P | Axis interface unit, 4 axes | P = PNP counterpart |
| CK3W-MD7110 | Digital I/O unit | 16 in / 16 out, NPN |
| CK3W-MD7120 | Digital I/O unit | 16 in / 16 out, PNP |
| CK3W-EXM01 | Expansion Master unit | Start of an expansion chain |
| CK3W-EXS02 | Expansion Slave unit | Add units downstream of the master |
| CK3W-CAX003A | Expansion cable, 0.3 m | Links master to slave |
| CK3M-CPU101 / 111 / 121 | Controller CPUs | The platform these units expand |
Omron conflicts with itself on one detail: the ia.omron.com lineup table describes the AX1515N output as DirectPWM, while Omron store and distributor pages describe it as DA output (true DAC). Omron publishes no digit-level legend for the 1515 block, so the functional description above is confirmed but the exact encoding is not.
Where these parts get used
- Multi-axis CK3M machine where four servo axes need encoder feedback above 1 MHz and the controller has no local axis ports
- Expanding digital I/O on a CK3M cell that has run out of local points
- Extending a CK3M chain with a second expansion Master and Slave pair over a 0.3 m cable
Which model do you need
- Confirm the controller is CK3M or CK5M first — these units do not fit CK1, CJ or NX platforms.
- Match output polarity: N units are NPN, P units are PNP, and a mismatch will not drive your field devices.
- A chain needs an EXM01 Master and at least one EXS02 Slave plus the CAX003A cable between them.
- Check the AX1515N output type against your motion design, because Omron's own sources describe it two different ways.
All 10 Omron CK3M / CK3W Axis & I/O Units SKUs
Every part number below links to its own page with full specifications, compatibility notes and stock status.
Frequently asked
Can I use CK3W expansion units with a CJ or NX controller?
No. CK3W units expand the CK3M programmable multi-axis controller only. They are not general-purpose I/O and will not work on CK1, CJ-series or NX platforms.
What does the N or P on a CK3W unit mean?
Output polarity. CK3W-AX1515N and CK3W-MD7110 are NPN versions; CK3W-AX1515P and CK3W-MD7120 are the PNP equivalents. Both the axis interface and the digital I/O units come in a matched polarity pair.
How many axes does a CK3W-AX1515N handle?
Four. It is a 4-axis interface unit with DA output accepting pulse-plus-direction or phase-differential command, encoder feedback to 10 MHz via digital quadrature or serial, and 16 digital inputs and 16 outputs alongside the motion channels.
Is a CK3W-MD7110 a relay unit?
No. It is a digital I/O unit with 16 inputs and 16 transistor outputs, NPN, measuring 31.6 x 90 x 80 mm. There are no mechanical relay contacts in the CK3W family — for relay outputs in a controller expansion you would use the DRT2 ROS units instead.
What do I need to add more expansion units?
An expansion chain runs from a Master to a Slave over the CK3W-CAX003A 0.3 m cable: CK3W-EXM01 is the Master and CK3W-EXS02 the Slave. Add EXM01 plus EXS02 pairs to grow the chain beyond a single master.
Specification sources
Specifications on this page were checked against Omron's own documentation. If a figure here disagrees with your datasheet, the datasheet wins — tell us and we will correct it.
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