In harsh environments, we typically must install resolvers as feedback devices to survive the extremes of the application. Very few of the stepper drives/controls are configured to support resolvers, so Empire Magnetics has for many years provided an RDE product – Resolver to Digital Encoder – to support the resolver and output Encoder type A, B, Z signals. Some customers have issues with loss of power which equals loss of position, and for multi-turn applications, absolute position information is better than incremental. Empire Magnetics Inc. has addressed both of these issues in the new product, Encoder Resolver Digitizer or ERD.
For those who are happy with incremental feedback, Empire has retained the primary function of resolver to encoder A, B, Quadrature and Z reference signals. They have also added an up/down counter that tracks absolute position over multiple turns. In addition, there is a feature that captures the last position in the case of a power failure. This absolute position information is available via Ethernet. Commands to zero or install an offset number are also available.
Incremental resolution is set at 1,024 cycles per revolution. Common quadrature detection circuitry will decode this to provide 4,096 counts per revolution. However, a software command can be change resolution to 16,384 counts per turn of the resolver.
The up-down counter has a range of -2147483648 to counts. At a resolution of 4096 counts per turn of the resolver, that unit supports 524,288 turns in either + or – direction from the zero point. Of course, operating in a mode where the direction reverses will keep the counters centered around the zero reference. If you are interested in learning more about Resolvers for Stepper Drives & Controls or want to implement an Empire Magnetics product into your process, contact a Cross expert!
