Measurement Computing Micro 488/EX rev.2.1 - Manual (Page 28)

Section 2 Getting Started
2.14
Selecting RS-232 or RS-422 Signal Levels
J205 J206
RS-422 RS-232
Shorting Plug
2.8.2 Serial Signal Descriptions
The Micro488/EX is equipped with a standard DB-25S connector on
its rear panel and requires a standard DB-25P mating connector. The
Micro488/EX's connector is configured as DCE type equipment for RS-232
communications, which means the Micro488/EX always transmits data on
Pin 3 and receives data on Pin 2. The following lists and describes the RS-
232 and RS-422 signals provided on the Micro488/EX.
Rear View of the Micro488/EX's Serial Connector
-RXD -TXD
CTS RTS
+TXD +RXD
+VTEST +VTEST
GND
1 13
14 25