Measurement Computing Micro 488/EX rev.2.1 - Manual (Page 27)

Section 2 Getting Started
2.13
2.7.2 Peripheral Pass-Thru Features
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. Refer to Section 7 for more information.
SW1 View for Peripheral SRQ on Last Serial Terminator
OPEN
1 2 3 4 5 6 7 8 DOT
Switch
Side
View
OPEN
1 2 3 4 5 6 7 8
SRQ on Last
Terminator Disabled
SRQ on Last
Terminator Enabled
2.8 Serial Interface
The Micro488/EX 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/XT/AT/PS2 or
compatible, the RS-232 level should be selected. If it will be connected to a Macintosh
512K/Plus/SE/II, the RS-422 level should be used. For connection to other computers,
refer to the manufacturer's manual to determine which levels are supported.
2.8.1 RS-232/RS-422 Signal Level Selection
The Micro488/EX'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 of the pins on the shorting plug are
inserted correctly.