V258-ZB21 DynamicSignals 4-Channel Synchro-to-Digital Converter

The V258 is a double-width, C-size, register-based, VXIbus module which functions as a multi-turn resolver-to-digital or synchro-to-digital converter. This module is available in either two-channel or four-channel versions.

Each channel is monitored by a single-speed, tracking resolver-to-digital or synchro-to-digital converter. Separate registers are provided for turn count and angle data. The module can continuously scan all channels and store the data in internal registers. The module can be directed to stop scanning the inputs to allow simultaneous angle measurement of all channels. While scanning is disabled, the turn counters internally track the inputs to prevent loss of data.

The V258 may be operated in absolute angle mode (in which the current angle is stored in the data registers) or in the offset mode. The offset mode is used to specify a reference point to reduce the amount of overhead required to monitor turns correctly. In the offset mode, the user may assign a reference point by setting a channel’s angle-and-turns count data to the desired value. The present angle value now becomes the zero degree angle position for calculating angle information.

To further reduce overhead and eliminate the need for polling, the V258 utilizes interrupts to signal when a given angle and turn value have been reached. Each channel has a 32-bit compare register which describes a channel compare point. This register contains a 16-bit angle value and a 16-bit turn value. When a channel input value matches or passes through both values, an interrupt may be generated. This eliminates the need for the host computer to constantly monitor each channel. An interrupt may also be generated when a channel’s converter detects a Loss-of-Signal.

Angle resolution is user programmable for 10, 12, 14, or 16 bits. The bandwidth for each channel is also programmable. Each channel’s converter may be programmed for higher precision in the higher resolution mode or faster settling in the lower resolution modes. This allows the converter to settle faster for step inputs.

The V258 supports both static and dynamic configuration. Access to the module’s operational registers is via memory locations pointed to by the Offset Register within the VXIbus Configuration Register set, using A24/A16, D16 data transfers.