(1) The internal microcontroller takes a snapshot of the disk every 7 msec. and stores the position in memory. It responds immediately to a "report position request" by sending this value which is always the most current position.
(1) Mode is always restored from non-volatile EEPROM on power-up; however, there are separate SEI commands for setting the RAM copy only, or both the RAM copy and the non-volatile EEPROM copy.
The analog version of the A2 has a 12-bit DAC on the output which feeds to 2 lines that are otherwise used for the BUSY handshaking pair. This DAC has a full range of 0 to 4.095 volts which is 1 milli-volt per bit. The value which the internal microcontroller sends to that DAC is the same as the digital value that it sends to the host. Since the resolution (which represents the number of codes per revolution) is field programmable, the range of the DAC will also follow that setup. Our default resolution is 3600 codes per revolution which yields 1 count per tenth of a degree. This makes the DAC output equal to 1 milli-volt per tenth of a degree or 0 to 3.599 volts. When the DAC needs to have the full range to 4.095 volts, the single turn resolution should be set to 4096. This is easily done with the available software which runs on a PC. Cable CA-MD6A-SS-MD6-6FT and either the SEI-USB or the AD2B adapter are needed to interface the A2 analog version to a USB port or RS-232 serial COM port.
Please Note: The BUSY handshaking lines are replaced by the analog output option. This means that only one device will be able to be connected to the SEI bus when using the analog output option.
EOL Sealed Housing Option - PCN 1021
This PCN is a formal notification that US Digital is discontinuing the Sealed Housing option for the following products:
A2 Absolute Optical Encoder
A2T Absolute Optical Inclinometer
H1 Ball Bearing Optical Shaft Encoder
H3 Ball Bearing Optical Shaft Encoder
S1 Optical Shaft Encoder
S2 Optical Kit Encoder
The Sealed Housing option provides the encoder with low level capability of surviving in moisture environments, however the encoder is NOT water proof or intended to be used in applications where this is required.
As part of our ongoing continuous improvement efforts, US Digital is updating our A2 and HD25A product lines design by utilizing surface mount devices for the detector and LED. Previously these were through hole devices. This change is transparent with the exception of minor cosmetic differences for the A2 kit style encoder, and Spacer Tool used in kit assembly process.
The A2 optical encoder is a 12 bit absolute rotary position sensor which reports a shaft angle within a single 360 degree rotation of a shaft. Unlike incremental, sometimes called relative, style encoders the A2 provides true (absolute) shaft position eliminating the need for a home or zero cycle after a supply voltage power cycle. The A2 communicates over a RS 485 style serial bus utilizing US Digital's SEI (Serial Encoder Interface) which allows for simple, quick and convenient networking of multiple SEI devices on a single network. PLCs, motion controllers and computers can also reside on the SEI bus as well by use of US Digital's SEI to USB interface device. For complete information about the SEI bus please refer to the SEI Communications Protocol webpage.
The A2 is also available with an optional analog output. The analog output option provides a maximum voltage range of 0 to 4.095 volts with 12 bit resolution. The output voltage may be easily scaled by simple SEI commands to provide other maximum voltage levels as well. From the factory the analog output voltage is set to 0 to 3.599 VDC range. Please note that with the A2 analog output option only one device may reside on a SEI bus.
US Digital designs and manufactures rotary absolute and incremental optical encoders, inclinometers and other precision motion control components used in a variety of applications including industrial automation, medical, robotics, textiles, renewable energy and more. US Digital is ISO 9001:2015 certified.