Configuration and Operation Chapter 3
GPIB-100A User Manual 3-4 © National Instruments Corporation
Mixed Mode Operation
If there are multiple Controllers and all of the same type are located on the same side of the
extension, the two GPIB-100A units can be set to Unbuffered and Buffered PPR modes
accordingly.
A. Unbuffered PPR Mode B. Buffered PPR Mode
P
P
R
P
P
R
BUF
UNBUF
O
N
O
N
represents the side of the switch you press down
123 123
Figure 3-2. Switch Settings for Parallel Poll Response Mode
Operating the GPIB-100A System
The GPIB-100A extension system is fully operational when power is applied to both units. In
TLC mode, it is sometimes necessary to power on the System Controller last, after the extenders
and all other devices are operating. This is necessary if the System Controller executes only one
IFC shortly after power-on.
The preferred operating mode is to keep both extenders and at least two-thirds of the devices on
both buses powered on when there is any GPIB activity.