The ASCII command interface provides access to the services offered by the Cascade Historian, such as configuring histories for data points and sending queries. A complete list is shown in the Commands reference.

The command interface model is basically client-server, whereby the client initiates all exchanges and must wait for the server (the Cascade Historian) to respond. This interface receives and returns ASCII IPC messages, which are ASCII strings with NULL termination. They can be transmitted by either the Cogent C API (see below) or by using the C function Send().

The command interface can be used at run time, and is also used to configure the Cascade Historian. Configuration commands can be stored in a configuration file which is processed before the Cascade Historian opens its interface to any user application.

See Configuration and Sending Commands in this manual for details on the command interface.

The Cascade Historian Functions reference section of the Cogent C API includes a group of C functions that facilitate access to the Cascade Historian from the user's (client) application code. These functions are essentially wrappers on the IPC interface to the Cascade Historian's commands. Although the majority of these commands are ASCII, support is also provided for transferring data (resulting from queries) in the more efficient binary format (see HI_BufferIDRead and HI_Interpolate). A set of utilities for performing some commonly needed transformations on the binary data buffers is also included.

The Cascade Historian dynamic library is an extension to the Gamma language that facilitates access to the Cascade Historian from the user's (client) Gamma application. These functions are essentially wrappers on the IPC interface to the Cascade Historian's commands. Although the majority of these commands are ASCII, support is also provided for transferring data (resulting from queries) in the more efficient binary format (see hist_buffer_id_read and hist_interpolate). A set of utilities is also included for accessing and performing some commonly needed transformations on the binary data buffers.

The dynamic library is called histdb.so, loadable by a Gamma application using the DllLoad function as follows:

    DllLoad ("histdb.so")

The library and corresponding command is histdb.dlb for QNX 4.

class HI_stVALUE
{
      value; 	// the real-valued Y-axis data (normally the point value)
      xaxis;	// the real-valued X-axis data (normally the time)
}

The following table shows all the Cascade Historian commands, and the Cogent C API functions and dynamic libary functions that correspond to them. This table is also available in the Command/Function Correspondence section of the Cogent C API manual.

The following table lists a set of functions for accessing and performing some commonly needed transformations on the binary data buffers. This table is also available in the Binary Data Buffer Functions section of the Cogent C API manual.