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22 Chapter 1
Introduction
E2050 Software/Firmware Architecture
Using Application Software
This section summarizes how the software on a client computer system
works with the E2050 LAN/GPIB Gateway to complete I/O application
operations on attached GPIB instruments. For more information on how to
use your software with the Gateway, see the applicable software
documentation as listed in “Related Software Documentation”.
Establishing a
Network Connection
Before trying to perform an I/O application operation on the Gateway’s
GPIB interface and the GPIB bus, the LAN client software in the client
computer system establishes a network connection to the LAN server (the
Gateway). Once the client establishes a connection, the client can begin to
send I/O requests to the Gateway.
Maximum Client
Connections
The Gateway (LAN server) can have multiple clients connected and being
serviced at any given time. The maximum number of concurrent client
connections depends on memory usage in the Gateway, including the
number of clients and the number of current sessions running on those
clients. However, at least 8, but not more than 15, client connections can be
running concurrently. Thus, if the maximum number of client connections to
the Gateway has not been exceeded, the connection is allowed to occur.
I/O Application
Operation
Although several instruments can be connected to the Gateway’s GPIB bus,
only one I/O application operation can occur on the GPIB bus at any given
time. Therefore, once a client’s request begins to execute on the GPIB, all
other client requests for operations on the GPIB must wait until the current
client request completes. Client requests are serviced in a first come, first
served manner, unless they are prohibited by interface or device locks.
Using Locks If a client has a sequence of I/O application operations to perform that
should not be preempted, the client should obtain a lock on the Gateway’s
GPIB interface or device. Once the client’s sequence has completed, it
should release its lock, allowing other clients access.
Closing a Network
Connection
When a client closes a connection, the Gateway frees up the resources
allocated to that client, including any locks, pending I/O requests, memory
usage, etc. Abnormal termination (for example, the network and/or client
goes down) is discussed in Chapter 5.