Section Two
Configuration and Installation
© National Instruments Corporation
2-5
GPIB-LPT User Manual
Listen Address and Control Function Selection
The GPIB-LPT interface board has eight onboard switches you can use to configure the GPIB
controller responsibilities. The lower five switches set the listen address of the external device(s)
that will be attached to the GPIB-LPT. This address is used to send a GPIB listen address to the
device(s) whenever the device(s) indicates that it is not a Listener. The three remaining switches
(REN, IFC, and SRQ) have the following special functions:
Note: An asterisk (*) after a signal name indicates that the signal is inverted (negative logic).
•
REN* Asserts/unasserts the Remote Enable (REN) line that places an instrument in remote
mode. The ON position enables REN. The OFF position disables REN.
•
IFC*
Enables/disables the Interface Clear (IFC) option on the GPIB-LPT. If enabled, the
GPIB-LPT issues an IFC when it is initialized. The ON position enables IFC on
initialization. The OFF position holds IFC unasserted.
•
SRQ* Enables/disables the Service Request (SRQ) option. If enabled, the GPIB-LPT
monitors the SRQ line through the Paper Error (PE) bit in the GPIB-LPT status
register. When the switch is positioned ON, the PE bit reflects the status of the SRQ
line. When the switch is positioned OFF, the PE bit is always low.
The GPIB-LPT factory default switch configuration is for device address 5, REN OFF, IFC ON,
and SRQ ON. Figure 2-3 shows the factory default switch settings for the GPIB-LPT.
Key
= side you must press down for default setting; Off = 1; On =
O
F
F
O
N
This side down for logic 0
This side down for logic 1
REN
IFC
SRQ
1
2
4
8
16
U18
Figure 2-3. Switch Setting for REN OFF, IFC ON, SRQ ON, and Address 5
(Default Setting)
