THE DM960
Principle of Operation
The DM960 resolver decoder provides an absolute multi-turn encoder in conjunction with AVG Automation's RL210 series multi-turn resolver, which has two resolvers: coarse and fine. The fine resolver is driven directly from the RL210 shaft, which in turn is directly coupled to the machine shaft. The coarse resolver is coupled to the main shaft through a 64:1 or 128:1 gear train. The gear train uses an antibacklash precision gear to assure full accuracy over the entire range. Thus the coarse resolver makes one revolution for 64 or 128 turns of the fine resolver. The coarse resolver counts the number of turns, while the fine resolver keeps track of the position in the last revolution and the two signals combined give absolute linear position over multiple revolutions. As shown in the diagram, the coarse and fine resolver rotor windings are excited from a common reference sinusoidal generator. The resolver analog output signals from the stator windings, after signal conditioning in the buffer amplifiers, are decoded to digital format in two independent Ratiometric Tracking Converters. The digital information from coarse (i.e., number of revolutions) and fine (i.e., position in the last revolution) resolvers is then superimposed in the coarse-fine alignment circuitry to determine the actual absolute position. The zero offset set by the front panel thumbwheels is continuously added to this value and the
resultant position is
displayed on the front panel display. The position information is also made available in a parallel format for external devices such as PLC's remote displays etc.
|
 |
Programmable Full Scale Offset for Easy Set-Up
You can mount the resolver on the machine without any concern for mechanically matching the resolver zero to the machine zero. Once the resolver is coupled to the machine shaft, the only thing you have to do is to bring the machine to a known position, say home position, and set an offset number using the front panel thumbwheel switches until the display reads zero. Now the resolver zero is aligned with the machine zero. This is especially useful during initial start-up in that it reduces the set-up time. The offset can also be used to compensate for any wear on the machine.
Variety of Outputs, Built-in PC-Handshake Permit Interface to Any PLC
BCD, natural Binary, or Gray Code output formats are available with a choice of TTL, PNP (sourcing) transistor, or NPN (sinking) transistor outputs. Optional PLC synchronization circuit provides an error-free method of interfacing BCD position data from the decoder to any PLC in the market. Upon
receipt of a data transfer command from the PLC, the stable data
is latched and made available to the PLC. The PC-Handshake,
being an edge-triggered device, allows stable data to be read
every scan by a PLC. |
