Controlling Camac instrumentation trough the USB port
R. V. Ribas 1*, R. V. Ribas 1
1 Instituto de Física - Universidade de São Paulo
In many laboratories, camac instrumentation like ADCs, TDCs, scalers, etc., even if are still very useful for data acquisition in low energy nuclear physics, they are becoming almost useless. Most of the common interfaces of the camac crate controller to micro computers are no longer available in modern computers (like ISA slots, GPIB boards, etc.). Also, in many applications only a few modules are plugged into the camac crate, that is a quite a heavy and noisy unit. In order to have a portable and simple interface to personal computers, we are developing interface boards that can accommodate a small number of camac modules connected to a standard USB port (both 1.1 and 2.0). These interfaces include a micro controller to handle the trigger signals, the related camac operations, event formatting, buffering and data transfer to the computer. The first version of the interface is limited for two specific modules we have in our Laboratory (an Ortec AD811 8x2048 channels ADC and a LeCroy 2228A 8x2048 channels TDC). A small power supply is included in the system, making it quite low weight and portable. Typically 4 us is spent to process each camac read operation and about half this time to dataless operations. A new interface, capable of handling four camac units was also developed and is now being tested. This new interface is be able to handle virtually any kind of camac module. A standard camac crate controller based in these boards is now under development. Details about the performance of these interfaces will be presented.