Using VXI-11, each operation is blocked until a VXI-11 instrument handshake returns. Using HiSLIP, data is sent to the instrument using the "fire and forget" method with immediate return. Thus, a successful return of a VISA operation such as viWrite() ensure only that the command is delivered to the instrument's TCP/IP buffers. There is no confirmation that the instrument has started or finished the requested command.
HiSLIP protocol
The high-speed LAN instrument protocol (HiSLIP) is the successor protocol for VXI-11 for TCP-based instruments specified by the IVI Foundation. The protocol uses two TCP sockets for a single connection - one for fast data transfer, the other for non-sequential control commands (e.g. Device Clear or SRQ).
HiSLIP has the following characteristics:
High performance as with raw socket communication
Compatible IEEE 488.2 support for message exchange protocol, device clear, serial poll, remote/local, trigger, and service request
Uses a single IANA registered port (4880), which simplifies the configuration of firewalls
Supports simultaneous access of multiple users by providing versatile locking mechanisms
Usable for IPv6 or IPv4 networks
Encryption and authentication supported with HiSLIP 2.0
For more information, see also the application note 1MA208: Fast Remote Instrument Control with HiSLIP.