In parallel to the Telescope Control System (TCS), we have a development system running that is used for testing, and which actually provides a full spare for the TCS. The hard disc of the development system has failed, and we need to replace the disc to both run the development system and as a spare. A shot term workaround solution was designed to allow to reboot the system using floppy discs. It has been difficult to find replacement (solid state) discs, but we were able to ordered 4 of them to have one replacement and one spare for each of the two systems. One of the discs was installed in the development system and found to work properly. If there are no problems with this disk in the coming months, the hard disk in the TCS itself will also be replaced to prevent possible failure while running.
Also the power supply for the TCS development system broke down. Together with an earlier broken one from the old development system (used for network application testing) they were both sent to England for repair. They are now on the way back.
There have been various reports of the TCS getting stuck which were likely traced to an intermittent disc access failure on the CPU board. Using a second CPU board over the last few weeks have shown no more problems and a replacement board should be purchased for the second faulty one. These are quite rare on the market, but we were able to order a refurbished one.
A returning issue noted in our search for spares is that the OS-9 operating system we have is relatively old and does not allow for more modern hardware, and it was decided to look if it was possible to port the TCS to an operating system that is in common use now and can use more modern hardware. One of the main requirements is that no major rewrite of the software is needed, where most changes should be on the level of system calls which is inevitable. It was found that Real Time Linux is the best (and cheapest) option. Such a system would also be an order of magnitude faster than the current system. A more detailed study is needed to see what is required to port the TCS. We do have a full set of spares which should last several years, so there is no strong urgencies.
Throughout the TCS, we use direct-current modules (to control the guide-camera focus, the telescope focus, the guide camera position, etc). A possible replacement module for all of them was identified and will slowly be introduced.
There is a general issue as for the network connection of the TCS with the general observing system. All the connections are through a common network, where the load from other traffic sometimes causes problems for the (rather old and limit) system on the TCS. The situation could be improved by providing a separate network for the TCS, and we are looking at how we might implement this.
Thomas Augusteijn 2013-12-02