In order to measure electric field distribution which is a very important parameter for the tuning of accel- erating cavities

Accelerator Lab of Tsinghua University has developed two measurement systems of longitudinal electric field distribution based on two different kinds of network analyzers. In designing the systems

Visual Engi- neering Environment (VEE)

a programming language

is used

and a new technology called Virtual Instruments is in- troduced. Direct I/O is a function module in VEE

and by adopting it to read from and write to instruments

there is no need to take care of bottom protocols

thus decreasing designers’ workload. The systems provide a friendly interfaces for users

demand less from users

and bring in more efficiency and stability.