Vaccess

Vaccess is the core of the Vsystem architecture. It is a user-extendable, real-time, in-memory database and library of access routines. Vaccess holds and transmits data and functions as an event-driven bus, providing notification of change upon request.

Vaccess maintains a responsive, secure, memory-resident data description of your facility. From ASCII text files, a GUI or by software, Vsystem generates a real-time database configured for your application. You can divide the database into many databases distributed among the computers of the system. Additionally, you can have a mix of computers running supported operating systems in the network, and they can all access the database. Security can be controlled per database or per channel. In a distributed, networked environment, although a database resides on only one computer, all other computers in the network have access to that single copy. Optionally, events generated from that database update remote applications with significant changes, ensuring efficient use of computing resources.

You can construct systems from small, easily defined, tested modules. In essence, Vsystem breaks complexity down into manageable pieces.

Features of Vaccess:

• Speed, manageability, security, and scalability
• High performance and memory resident
• Channel types: binary with text support, integer (8-, 16-, and 32-bit; each either signed or unsigned), single-precision floating-point, double-precision floating-point, string (2³¹ characters), and time (resolution 1 ns)
• All channels optionally time stamped
• Numeric channels can be arrays up to 2³¹ characters bytes
• Array channels can be circular buffers with each value optionally time stamped
• Each database can have up to 65,535 channels
• Up to 65,535 databases in a system, with any number on each computer
• Alarming with delayed alarms and with reference alarms
• Full programming interface
• Event-driven change notification on all fields
• Dynamic memory management
• User-defined conversion routines with parameters for non-linear conversion. User-defined conversion routines can be programmed or written as a script equation.
• Conversion routines can do gets and puts
• Multiple conversion routines per channel, each with its own conversion parameters
• User-written I/O routines
• 99% of fields are dynamically changeable
• Channels can be added dynamically to a running system
• All releases intercommunicate - no need to upgrade your old system when a new system is added
• 256 alarm priorities
• Database, channel, and field security
• Database checkpoint manager to ensure that disk copy is current in case of failure
• Application area and subarea fields supported for larger applications