SICL
Agilent Standard Instrument Control Library (SICL) is an I/O Library developed by Agilent (HP) that is portable across many interfaces and systems. SICL is a modular instrument communications library that works with a variety of computer architectures, I/O interfaces, and operating systems. Applications written in C/C++ or Visual Basic using this library can be ported at the source code level from one system to another with no (or very few) changes.
SICL uses standard, commonly used functions to communicate over a variety of interfaces. For example, a program written to communicate with a particular instrument on a given interface can also communicate with an equivalent instrument on a different type of interface.
VISA
Agilent Virtual Instrument Software Architecture (VISA) is an I/O Library designed according to the VXIplug&play System Alliance that allows software developed from different vendors to run on the same system.
Use VISA if you want to use VXIplug&play instrument drivers in your applications, or if you want the I/O applications or instrument drivers that you develop to be compliant with VXIplug&play standards.
USBTMC
Stands for USB Test & Measurement Class. USBTMC is a protocol built on top of USB that allows GPIB-like communication with USB devices. From the user's point of view, the USB device behaves just like a GPIB device. For example, you can use VISA Write to send the *IDN? query and use VISA Read to get the response. The USBTMC protocol supports service request, triggers and other GPIB specific operations. USBTMC allows instrument manufacturers to upgrade the physical layer from GPIB to USB while maintaining software compatibility with existing software, such as instrument drivers and any application that uses VISA. It is important to note that not all USB devices are USBTMC compliant. The device manufacturer has to add the support in the device firmware to support USBTMC.
