National Instruments NI-VXI

Chapter 3 Software Overview

DefaultWSScmdHandler (cmd)

DefaultWSScmdHandler is the default handler for the WSSwrt

interrupt, which InitVXIlibrary automatically installs when it

initializes the NI-VXI software. The current WSScmdHandler is called

whenever the local CPU Commander sends any Word Serial Protocol

command or query (other than BAV or BREQ). While Word Serial

operations are enabled, the WSScmd interrupt handler is called every

time a Word Serial command is received (other than BAV if a

WSSrd call is pending, or BREQ if a WSSwrt call is pending).

DefaultWSScmdHandler parses the commands and takes appropriate

action. If it is a query, it returns a response using the WSSsendResp

function. If it is a command, it calls the WSSnoResp function to

acknowledge it. If either a BREQ or BAV command is received via this

handler, it calls GenProtError with the corresponding protocol error

code (DOR violation or DIR violation). For unsupported commands,

the protocol error code sent to GenProtError is UnSupCom.

DefaultWSSEcmdHandler (cmdExt, cmd)

DefaultWSSEcmdHandler is the default handler for the WSSwrt

interrupt, which InitVXIlibrary automatically installs when it

initializes the NI-VXI software. The current WSSEcmdHandler is

called whenever the local CPU Commander sends any Extended

Longword Serial Protocol command or query. While Word Serial

operations are enabled, the WSSEcmdHandler is called whenever a

Longword Serial command is received. WSSEcmdHandler must parse

the commands and take the appropriate action. Because the VXI

specification does not define any Extended Longword Serial

commands, DefaultWSSEcmdHandler calls GenProtError with a

protocol error code of UnSupCom for every Extended Longword Serial

command received.

DefaultWSSLcmdHandler (cmd)

DefaultWSSLcmdHandler is the default handler for the WSSwrt

interrupt, which InitVXIlibrary automatically installs when it

initializes the NI-VXI software. The current WSSLcmdHandler is

called whenever the local CPU Commander sends any Longword Serial

Protocol command or query. While Word Serial operations are

enabled, the WSSLcmdHandler is called whenever a Longword Serial

command is received. The WSSLcmdHandler must parse the

commands and take the appropriate action. Because the VXI

specification does not define any Longword Serial commands,