VMEbus TCP/IP Instrument Protocol Specification VXI-11

http://www.cadfamily.com/downinfo/302227.html

B.2. CONNECTION MODEL
This section defines the connection model of the network instrument protocol, as well as the relationship between controllers, devices, network instrument clients, and network instrument servers. The term controller, as used in this specification, typically refers to the RPC client, while the term device typically refers to the RPC server. The only exception is when the roles are reversed for interrupts, which will be described further later in the specification.
As discussed in the overview at the beginning of this specification and shown in Figure B.1, the network instrument protocol uses up to three channels between the controller and the device for passing network instrument messages. A network instrument connection is this set of channels:
Core Channel: Used to transfer all requests except the device_abort RPC and the device_intr_srq RPC.
Abort Channel: Used to transfer the device_abort RPC (optional for client).
Interrupt Channel: Used to transfer the device_intr_srq RPC from the device to the controller(optional for client).