Choosing the right sensing component for a sensors, encoders, and machine-safety project often comes down to a simple fork in the road: do you want a complete, ready-to-use length measuring system, or do you want a bare encoder that you wire into your own control circuit? The products here cover both paths, with prices ranging from $16.95 to $94.72. This guide breaks down what each one does, what it costs, and which use case it fits.
Quick take
For someone standing on a shop floor, the two complete counter systems - the Electronic Digital Length Meter Rotary Encoder Rolling Wheel Distance Counter and the 300ppr Rotary Encoder Digital Meter Counter with Wheel & Mounting Bracket - are turnkey solutions. They use an encoder plus a digital readout to show a length measurement. The other two - the Oak / Grigsby 91Q128 and the EC11 - are components. They don't display anything on their own; instead, they send signals that a PLC, counter, or microcontroller can interpret.
Comparison at a glance
| Product | Price | Bar | Best fit |
|---|---|---|---|
| Electronic Digital Length Meter | $94.72 | Complete in-line length measurement | |
| Digital Meter Counter | $86.20 | Modular roll-length counting | |
| Oak / Grigsby 91Q128 | $16.95 | Adding quadrature feedback to a 5V control system | |
| EC11 Rotary Encoder | $21.00 | Rotary input |
Decision matrix
- Need a complete distance readout for control-panel use? Choose the Electronic Digital Length Meter.
- Need a turnkey length counter for stopping or starting equipment? Choose the Digital Meter Counter.
- Need a bare incremental encoder for a logic board or PLC? Choose the Oak / Grigsby 91Q128.
- Need a panel knob for manual settings? Choose the EC11 rotary encoder.
Product notes
Electronic Digital Length Meter Rotary Encoder Rolling Wheel Distance Counter US
This is the most complete package in the group. It pairs a black digital counter with a rolling wheel, so you can measure cloth, tube, or similar materials without a tape measure. The counter can display feet, inches, meters, or yards, and its range extends to 999,999m. It also has dual relays, which lets it control two devices at once - handy for triggering an alarm or cutting a motor at a preset length. The body mixes plastic, aluminium alloy, and rubber, and the unit weighs about 1.2kg. The main limitation is the cost: it's the most expensive option in this comparison. If your job only needs rotational feedback, this complete system is more than you'll need.
300ppr Rotary Encoder Digital Meter Counter with Wheel & Mounting Bracket
A close cousin to the first product, but it takes a modular approach. Instead of one all-in-one counter, you get a digital meter, a 300ppr rotary encoder, a wheel, and a mounting bracket. Each wheel revolution produces 300 pulses. The meter has a relay output, so it can stop or start external equipment at a set length, and it supports an early-warning value for approaching a target. The working voltage is 110-220V with a US plug. It's a significant investment, and the separate encoder needs to be attached to the bracket before use. This system suits modular length-measuring jigs rather than permanent OEM installations.
Oak / Grigsby Rotary Encoder - 128 Pulse/Rev - 91Q128 - 2 CH Full Quadrature
The least expensive option in this group. You get an incremental encoder with a 1/4-inch stainless steel shaft, sealed sleeve bearing, and a 4-inch cable ending in bare wire. It outputs quadrature signals with Channel A leading Channel B by 90 degrees in clockwise rotation, and it runs on 5V TTL logic. The 91Q128 model produces 128 pulses per revolution. It also includes mounting hardware. The limitation is that it's a bare encoder: it sends incremental signals, so you'll need your own PLC, counter, or microcontroller to convert those pulses into position or length.
One 5PIN EC11 30 Position Rotary Encoder With Push Switch Split Shaft
This is the compact panel component. The EC11 encoder gives you 30 detent positions, a split shaft, and a push switch that can serve as a second input. The 5-pin layout includes the standard encoder signals plus the switch, so you can wire it into a controller or radio panel. The shaft extends about 12.5mm, which gives a reasonable depth for knob installation. Its main limitation is its manual operating intent: it is built to be turned by a person, so it's best suited to control-panel duties. If your project needs a detent-feel knob with a push-to-select function, this is the one.
Final recommendation
- Best for complete length measurement: Electronic Digital Length Meter.
- Best for modular length measuring: Digital Meter Counter.
- Best for adding rotary feedback to a logic circuit: Oak / Grigsby 91Q128.
- Best for compact rotary input: EC11 rotary encoder.
