KPCI-488LPA GPIB Controller Interface Card Quick Start Guide
8
KPCI-488LPA-903-01 Rev. B /
January 2020
Handshake lines
Three handshake lines control the transfer of data/messages between devices:
DAV (Data Valid)
:
Used to indicate the availability and validity of information on the DIO signal lines.
NRFD (Not Ready For Data)
: Used to indicate readiness of devices to accept data.
NDAC (Not Data Accepted)
: Used to indicate acceptance of data by device.
System management lines
The following five system management lines manage the flow of control and data bytes across the interface:
EOI (End or Identify)
: Used (by a talker) to indicate the end of a multiple-byte transfer sequence or, in
conjunction with
ATN
(by a controller), to execute a polling sequence.
IFC (Interface Clear)
: Used (by a controller) to place the interface system, portions of which are
contained in all interconnected devices, in a known quiescent state.
SRQ (Service Request)
: Used by a device to indicate the need for attention and to request an
interruption of the current sequence of events.
ATN (Attention)
: Used (by a controller) to specify how data on the Digital I/O signal lines are to be
interpreted, and which devices must respond to the data.
REN (Remote Enable)
: Used (by a controller) in conjunction with other messages to enable or disable
one or more local controls that have corresponding remote controls.
KPCI-488LPA block diagram
The KPCI-488LPA has a 1 KB on-board FIFO buffer (First In First Out) to maximize the data transfer rate. The
CPLD (Complex Programmable Logical Device) coordinates the data flow between the PCI controller
(Peripheral Component Interconnect), FIFO buffer, and GPIB bus.
Figure 6: KPCI-488LPA block diagram
The FIFO can buffer data from the master (either from the KPCI-488LPA or external device) when the target is
busy. Therefore, the efficiency will be significantly improved when transferring large blocks of data.
