Incremental encoder, counter for motion control
Tews Technologies offers a line of embedded I/O board products, including this standard single-width 32-bit PMC module with six channels.
Tews Technology offers the TPMC117, a standard single-width 32-bit PMC (PCI Mezzanine Card) module with six channels. It operates as a standard SSI (Serial Synchronous Interface) interface controller, a SSI “listen only” device, an incremental encoder, or a general-purpose counter. [PCI stands for peripheral component interconnect.]
The standard SSI interface controller provides a clock burst output to the absolute encoder and receives the returned positional data. The SSI interface controller operates with a programmable clock rate from 1and the SSI clock rate of the observed SSI interface can be in the range of 1µs to 15µs. In both modes the data word can be encoded in binary- or in gray code and with odd, even, or no parity.
The 32-bit incremental encoder counter is a preloadable up-and-down counter. The counter is programmable for single, double, and quadruple analysis of the encoder signals. In conjunction with the isolated 24-V digital inputs, it provides the possibility of automatic preload of the counter whenever the motion system passes a reference position. The 32-bit general purpose preloadable up-and-down counter can be fed with an internal clock or with external signals. Both counter modes offer a 32-bit preload register, a 32-bit compare register and various count modes. A multiple channel read function latches the actual values of all enabled channels whose values can then be read without interfering with normal continuing function.
In addition the TPMC117 provides a 16 bit down-counter with preload register which allows timing intervals of up to 65ms. It can be used as reference timer for closed-loop applications or as trigger for the multiple channel read function.
All data inputs are isolated. The level of the input signals can be either RS-422 or TTL. The input signals pass a digital filter for noise suppression before being used. The level of the SSI clock output signals is RS-422. Each of the six motion control channels of the TPMC117 offers one isolated 24-V digital input. The input circuit ensures a defined switching point and polarization protection against confusing the pole. The input has an electronic debounce circuit. All six 24-V digital inputs can generate an interrupt, triggered on rising or falling edge. Depending on the selected mode the input can be used as general purpose input or reference input. Software support for major operating systems is available.
—Edited by Lisa Sutor , Control Engineering contributing editor