TE Connectivity (USA) offers a range of draw-wire sensors based on CiA 406 conformant rotary encoders. They come in housings made for harsh environments.
Draw-wire sensors are used since many years in commercial vehicles, medical equipment, and other applications to measure length, speed, and acceleration or deceleration. CANopen is a common communication interface. Conformity to the CiA 406 profile for encoders provides some interoperability with control units. TE Connectivity offers a range of draw-wire sensors in robust housings.
The SR1H draw-wire sensor is part of a product series built for wet environments and outdoor applications. It comes in two ranges: for 0 mm to 3175 mm or 0 mm to 4445 mm measurements. Every unit is shipped with a handy mounting bracket giving the user the possibility to orient the measuring cable to one of four different directions. The CANopen interface conforms to CiA 301 (version 4.0.2) and CiA 406 (version 3.2). The node-ID is configurable by means of a DIP-switch or LSS communication services (CiA 305). The default node-ID is 1.
The sensor features a 12-bit resolution. Celestro is the supplier of the rotary encoder element. The device comes in an IP67-rated enclosure.
In order to take measurements, the transducer's body is mounted to a fixed surface and the stainless steel cable is attached to the movable object. As the object moves, the transducer produces an electrical signal that is proportional to the cable's linear extension or velocity. To maintain cable tension, a spring is coupled to the spool. The spool is coupled to the shaft of the encoder element. As the transducer's cable extends along with the movable object, it causes the spool and sensor shafts to rotate. The length measurement is mapped into a PDO, which is sent via the CANopen network to displays, host controllers, or data acquisition systems.
The U.S. company also provides its draw-wire products with J1939 or Devicenet connectivity. The SGH series is suitable for length measurements of up to 2032 mm respectively up to 3048 mm. For measurements up to 10 m, the company offers the SKH series.
News and reports