In the design of the digital transmission system in \ac{ALMA} Observatory, the optical link is established by a set of transmitter and receiver transponder pairs, the receiver unit is an open board where the transponder can be easily accessed when the technician or engineer requires to remove or perform special adjustments. However, the transmitter is enclosed in a particular chassis, where it is hard for any person to work with the transponder directly, therefore testing on this unit is a cumbersome task. The creation of a transponder test fixture provides several degrees of freedom in the testing and repair of transmitter modules with ease.
In order to accomplish this goal. It was studied which set of functions would be available with the purpose to identify the required hardware and signal connections to retrieve to this unit. According to this study, I analyzed the electronic schematic for retrieving the full list of materials such as SMA connectors, \ac{LVDS} signals, optical feed-throughs, \ac{CAN} bus connections, power outlets, and boards. The physical layout was designed and built later according to specifications, the used board for testing the transponder (formatter) was configured to comply with the laboratory requirements, and connections were finally made according to the plan.
After the transponder test fixture was implemented as a standalone unit, a program with the aim to control this device was developed in Python language. The tool, which graphically displays information over a regular console window, communicates over low-level \ac{CAN} bus link to the transponder test fixture. This script displays formatter status, transponder alarms, and debugging modes. The user can change any of those parameters by interacting with a series of keystrokes shown in the interactive window.