Absolute Encoders for Feedback for CNC/PLC



Developed to meet a wide range of feedback applications, Newall's Absolute linear encoders provide a true absolute position immediately upon power-up. The encoder does not use batteries or static memory to retain the positional data. True position can be reacquired once power is applied, regardless of duration or power-off movements. The encoder is ideally suited for linear motor and other high velocity measurement applications including CNC/PLC feedback, pick and place machines, automotive transfer lines, packaging machines, PC-based systems and more.

 
signal Model Description
RS232 SHG-A2 RS232 serial communication is typically used to interface with PC "COM" ports. This EIA standard allows for data transmission from one transmitter to one receiver at data rates up to 20K bits/second and distances up to 15m at the maximum data rate. A serial to USB converter is available to allow interface via a USB port. SHG-A2 - RS232 Protocol (241k)
RS485 SHG-A4 This EIA standard meets the requirement of a multi-point communication network, which as standard specifies up to 32 drivers and 32 receivers on a single two-wire bus. A key feature is the ability to address individual devices. This model can be ordered with unique address tags to facilitate multiple devices on the RS485 bus. SHG-A4 - RS485 Protocol (241k)
SSI This EIA standard meets the requirement of a multi-point communication network, which as standard specifies up to 32 drivers and 32 receivers on a single two-wire bus. A key feature is the ability to address individual devices. This model can be ordered with unique address tags to facilitate multiple devices on the RS485 bus. SHG-A4 - RS485 Protocol (241k)
SHG-AB SSI Binary | Data Bits: 24 | Parity: None SHG-AG, SHG-AB - SSI Protocol (188k)
SHG-AG SSI Gray Code | Data Bits: 24 | Parity: None SHG-AG, SHG-AB - SSI Protocol (188k)
SHG-AS SSI Gray Code w/TTL incremental signals (typically used for Siemens controls) Data Bits: 24 | Parity: Even. SHG-AS - SSI w/Parity Quad Protocol (226k)
Fanuc Serial SHG-AF This is a proprietary absolute encoder protocol. It is used exclusively with Fanuc CNC products that require absolute positional feedback. SHG-AF - Fanuc Protocol (305k)

How Do They Work?

Uniquely coded inserts are placed between the precision balls in the scale. The inserts contain a small magnet that can be detected by a series of hall sensors contained in the reader head. The density of the inserts and the detectors within the reader head allows the encoder to determine fully absolute position. Once the encoder has determined the true absolute position it is then a matter for the Digital Signal Processor (DSP) to handle communication of the positional data to the controller. Being a DSP based absolute system capable of a high level of processing; the encoders are error mapped during manufacturing against a laser interferometer. This error map is stored in FLASH memory allowing it to be applied in real-time thus resulting in a highly accurate encoder.

 

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