SARAO, Cape Town, South Africa
The original Controller Area Network (CAN) protocol, was developed for control and monitoring within vehicular systems. It has since been expanded and today, the Open CAN bus protocol is a leading protocol used within servo-control systems for telescope positioning systems. Development of a CAN bus monitoring component is currently underway. This component forms part of a greater software package, designed for an Antenna Positioner Emulator (APE), which is under construction. The APE will mimic movement of a MeerKAT antenna, in both the azimuth and elevation axes, as well as the positioning of the receiver indexer. It will be fitted with the same servo-drives and controller hardware as MeerKAT, however there will be no main dish, sub-reflector, or receiver. The APE monitoring software will receive data from a variety of communication protocols used by different devices within the MeerKAT control system, these include: CAN, Profibus, EnDAT, Resolver and Hiperface data. The monitoring software will run on a BeagleBone Black (BBB) fitted with an ARM processor. Local and remote logging capabilities are provided along with a user interface to initiate the reception of data. The CAN component makes use of the standard SocketCAN driver which is shipped as part of the linux kernel. Initial laboratory tests have been conducted using a CAN system bus adapter that transmits previously captured telescope data. The bespoke CAN receiver hardware connects in-line on the CAN bus and produces the data to a BBB, where the monitoring software logs the data.
