S

PECIFICATIONS

E LECTRICAL Input powerV CC : +5VDC ±0.5 VDC @ 60 mA Light sourceScreened infra-red LED; rated life >100,000 hours Output SignalsSingle-ended TTL-compatible square waves M ECHANICAL Materials Encoder body Disc HubMolded PPS 40% glass (R-4)Vacuum-deposited chrome pattern on glass or plasticAluminum Weight Read head0.25 oz (7 g) max without cable P ERFORMANCE Frequency response125 kHz, all channels Endplay? 0.010 inches (0.254 mm) E NVIRONMENTAL Operating temperature-40°F to +212°F (-40°C to +100°C) Storage temperature-40°F to +212°F (-40°C to +100°C) Virtual Absolute ( VA ) Industrial encoders VA discs and scales are similar to incremental discs and scales in that they contain a cyclic track and an index track. In an incremental encoder, the index occurs at one place in the full travel, but in a VA encoder, the index track is a continuous serial code (similar to a bar code). You don't know position immediately upon start-up, as you do in a conventional absolute, but after a very short travel , in either direction and starting from anywhere , you know exactly where you are. With a 1024-line disc, the initialization angle is 3.5°; with a 2048-line disc, it's 1.9°. From then on, the encoder is truly absolute.Our Model VG Interpolating Decoder is only 1" x 2". It contains a patented high-speed decoder for the pseudorandom index track, and it incorporates quarature decoding to increase resolution by a factor of 4. In addition to the natural binary position output, a status bit is provided to tell you when the encoder is initialized. This bit is at a logic high whenever the initializing motion is not yet complete, or when some other problem such as supply voltage interruption, electrical noise, damage, or fouling of the disc interferes with the proper code sequence from the index track. When these self-tests are all satisfied, the status bit is low, indicating the position data output is valid. Please refer to the Model VG data sheet for complete details. Commutation Tracks If your motor has P poles, then you need a disc with N cycles/rev of commutation tracks, where N = P/2. The three commutation signals are phase-shifted 120° electrical from each other.
1 cycle

C1

120°

C2

120°

C3

As part of our continuing improvement program, these specifications are subject to change without notice.

7700

Gurley Precision Instruments514 Fulton StreetTroy, NY 12180 U.S.A.(800) 759-1844, (518) 272-6300, fax (518) 274-0336, Online at www.gurley.com, e-mail: info@gurley.com

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