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Calt String Encoders Product Review – Easy To Use And Highly Reliable

Here is what a customer had to say about the Calt brand string encoders after using them in an application involving controlling hydraulic cylinders:

“Great quality and accuracy. I have purchased 3 of these encoders. Takes only about 10 days for shipping which is not bad from China. I resold these with a module to a customer that used them on hydraulic cylinders. Works perfect.”

These draw-wire position sensors, or string encoders for short, by Calt are highly efficient linear displacement measuring devices. They work based on an ingenious design principle that utilizes a special steel cable that reels in and out on a spring-loaded constant diameter spool. The rotation of the spool is converted into electrical signals by an incremental encoder, a multi-turn potentiometer, or a multi-turn absolute encoder depending on the model of string encoder you choose for your application.

A convenient listing of many of the models of string encoders by Calt that are available for purchase are given in the next section of this product review.

The Models, Where To Buy, and Prices

Product: Calt CESI Series String Encoders

* String encoder with 1000 mm travel and incremental encoder A, B, and Z outputs
Available from Amazon.com for $121.97

* String encoder with 2000 mm travel and incremental encoder A, B, and Z outputs
Available from Amazon.com for $168.00

* String encoder with 3000 mm travel and incremental encoder A, B, and Z outputs
Available from Amazon.com for $218.00

Product: Calt CWP Series String Encoders

* String encoder with 500 mm travel and analog 4-to-20 mA outputs
Available from Amazon.com for $110.00

* String encoder with 500 mm travel and analog 0-to-5K ohms outputs
Available from Amazon.com for $112.00

* String encoder with 1000 mm travel and analog 0-to-5 volts outputs
Available from Amazon.com for $120.00

* String encoder with 1000 mm travel and analog 4-to-20 mA outputs
Available from Amazon.com for $110.00

* String encoder with 1000 mm travel and analog 0-to-5K ohms outputs
Available from Amazon.com for $120.00

Product: Calt HS-M3000RM String Encoder

* String encoder with 3000 mm travel and multi-turn absolute encoder with Modbus RTU RS485 outputs
Available from Amazon.com for $645.00

Product: Calt CESI Series String Encoders Paired With Digital Display

* Digital display unit paired with string encoder with 1000 mm travel
Available from Amazon.com for $190.00

* Digital display unit paired with string encoder with 2000 mm travel
Available from Amazon.com for $230.00

* Digital display unit alone
Available from Amazon.com for $48.00

Low Cost – Compact – Easy To Use

The Calt CESI and CWP series, and HS-M3000RM string encoder products are a low cost, compact, and easy to use sensor based cable-extension transducers. The full stroke range depending on the model you choose is 500 mm, 1000 mm, 2000 mm, and 3000 mm. The draw wire sensor is available with incremental encoder push-pull outputs A, B, and Z, analog outputs 4-to-20 mA, 0-to-5V, or 0-to-5K ohms, or multi-turn absolute encoder serial outputs that are Modbus RTU RS485 compatible.

As mentioned, the rotational angle measurement device is a sensor of one of the following three types depending on the model of string encoder you order:

1. An incremental encoder with 2-channel A and B quadrature outputs and a third channel Z or index. These outputs are of the push-pull type or sometimes referred to as totem pole outputs. A push-pull output can both sink load current to GROUND through an NPN transistor, or source current to the load through a PNP transistor.

Both output connection options to the LOAD are shown in the diagram above.

The example with the LOAD connected to +V is the current sinking mode of operation. When the lower NPN transistor is turned on, there is a low resistance path for current to flow from V+ through the LOAD to GROUND.

The example with the LOAD connected to GROUND is the current sourcing mode of operation. When the upper PNP transistor is turned on, there is a low resistance path for current to flow through the LOAD from V+ to GROUND.

The push-pull output options would work especially well with interfacing to a PLC. If interfacing to 5-volt TTL or CMOS logic, or to microcontrollers or microprocessor chips powered by +5 volts, then some kind of signal voltage level conversion device would need to be used.

2. A multi-turn potentiometer and associated electronics that provide analog output choices of 4-to-20 mA, 0-to-5 volts, or 0-to-5K ohms.

3. A multi-turn absolute encoder with Modbus RTU RS485 serial outputs.

These string encoders convert the linear displacement motion of the cable reeling in an out into electric signals that are proportional to the displacement of the object whose linear movement is being measured.

 

Many Areas Of Application

The Calt string encoders can be used in many applications. These would include linear guide systems, cranes, piston and cylinder hydraulic lift systems, as displacement and deflection sensors, presses, lifts, bending machines, cranes, cable winches, forklifts, stage equipment, MRI and CAT scan patient table positioning, and so on.

 

More Product Specifications And Drawings Available At Amazon

Click on the specific product link above for the string encoder that you are interested in. You will be taken to the product page for that specific string encoder on the Amazon website. There you will find a listing of product specifications, mechanical drawings, cable wire color and signal identification, and more.

Please note that the color of the product you receive may be different from what is shown in the images above. Colors can vary by the batch they were manufactured in. The color of the string encoder you receive could be yellow, blue, or green. Again this can vary from one batch to the next.

Needing Technical Assistance?

If you have questions or need technical assistance, please indicate that in the comments section below. Or you can email me at clark@encoders101.com.

I will be glad to assist you in any way that I can. It is my goal to help you successfully incorporate a string encoder into your next application. You might need help with how best to interface a string encoder to your system. Be it PLC, computer, motion controller, digital display, or whatever, I can assist you with that.

I look forward to reading your comments below, and learning about your specific application, which string encoder you chose for your application, and how it is working out. Your feedback will help your fellow readers of my articles and blogs to be successful as well.

Clark Ludahl

 

 

 

 

 

Clark Ludahl

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