488 CONTROLLER
22
3.6.2 P
ERIPHERAL
P
ASS
-T
HRU
F
EATURES
In the Peripheral Pass-Thru (IEEE-488-to-RS-232 converter) mode, SW1-7 enables the interface to assert
the SRQ IEEE bus interface line to indicate that it has received the last-switch-selected serial terminator
character from the serial device.
Figure 3-15. Switch SW1: Enabling or disabling SRQ on last serial terminator in Peripheral mode.
3.7 Serial Interface
The 488 Controller has the ability to output signal levels that are compatible with either RS-232 or RS-422.
An internal DIP shorting plug determines which electrical specification is chosen. If the interface is to be
connected to an IBM
®
PC or compatible, select the RS-232 level. If it will be connected to a Macintosh
®
, use
the RS-422 level. For connection to other computers, refer to the manufacturer’s manual to determine
which levels are supported.
3.7.1 RS-232/RS-422 S
IGNAL
L
EVEL
S
ELECTION
The 488 Controller’s factory default signal levels are compatible with RS-232. To select RS-422 levels,
carefully remove the 8-position shorting plug with a small flat-blade screwdriver from J106. Install the
DIP jumper into J205, making certain that all shorting plug pins are inserted correctly.
Figure 3-16. Selecting RS-232 or RS-422 signal levels.
Switch
Side
View
DOT
1 2 3 4 5 6 7 8
OPEN
SRQ on Last
Terminator Disabled
1 2 3 4 5 6 7 8
OPEN
SRQ on Last
Terminator Enabled
Shorting Plug
RS-232
RS-422
