40m OAN telescope. First experience with ACS Observatorio Astronómico Nacional P. de Vicente, R. BolañoMarch 2004

40m OAN telescope. First experience with ACS MAN Servosystem specs. definition Our own control system OAN Servosystem Design, servosystem and integration for the OAN 40m dish: MAN Technologie (Germany)

Present status

Main Milestones Supporting tower finished 3 years ago. Electrical power for the moving part under works. Main reflector and receiver cabin being build up. Servo system under test in Germany. Software in ACU being developed in Germany. Panels already built and delivered by Cospal (Italy). Delivery: summer First cooled receivers: autumn 2005.

The Antenna Control Unit closes the control loop. controls the main drives, subreflector movement, mirrors, fans, vertex. performs the transformation from apparent (Ra, Dec) to (Az, El). moves the mount according to tables (T, Az, El) or (T, Ra, Dec).

The Antenna Control Unit The ACU runs under VxWorks. The ACU is composed of 2 Motorola boards on a VME crate. To command the ACU it is necessary to use sockets. No CORBA usage was planned in the design stage and therefore now it is not used.

CORBA evaluation during 2003 CORBA has never been used in the OAN previously. Last year we investigated the usage of CORBA and made some tests to verify that we could connect clients and servers written in Python and C++ across the LAN. The chosen CORBA implementation was OmniORB. We tested clients using Qt (Python and C++) for GUIs and MySQL. We missed some CORBA services in OmniORB.

ACS 3.0 installation on Debian In the OAN we use Linux / Debian as the default Linux distribution. In October we tried to use ACS 2.1 on Debian and we were unsucessfull, because Debian 3.0 provides gcc 2.95 and ACS needs gcc ACS 2.1 works under Red Hat 7.2. We tried in November 15 th ACS 3.0 on a Debian 3.0, using the GNU tools provided by ACS. After some minor modifications the installation was successfull.

First example using ACS 3.0 We got much help from Gianluca Chiozzi and Dirk Muders. The documentation is there but it requires some time to read it and more time to process it (timescale ~ weeks). We tested some ACS examples among different hosts. We made a first test using C++ to read a thermometer through the serial port and monitor the output by December 17 th.

Integration with native libraries: Qt and MySQL ACS runs in an account with a separate environment, allowing to use the compiler and other GNU tools provided by ACS. This is a problem when trying write a client which uses other tools from the OS like Qt and MySQL, since they are linked against a different libc library. g++3.2 (ACS) and g (Debian 3.0) produce code which are binary incompatible.

ACS on Debian 3.1. Our current solution By the end of January we tried to install ACS in a Debian 3.1 distribution. Debian 3.1 will be next stable version in a few months and it uses g We compiled ACS using as many tools as we could from Debian instead of using them from ACS Now we can write clients which use ACS, Qt and MySQL.

A weather station simple client using ACS We have now a very simple GUI client which reads a simple weather station through the serial port and shows the current weather status. A second client logs the data into a MySQL database.

Final remarks ACS fits our needs since it provides real time process communications and aditional services. It is well supported by a team of people. It will probably have a long term life (ALMA). We have learned the hard way, bumping into problems, reading documentation and asking in the lists. Many problems found do not come from ACS. Still learning how to use it, much to learn yet. The ACS team is very supportive.