Agilent Technologies 1670G Series Service Manual page 222

Theory of Operation
RS-232-C
RS-232-C
The logic analyzer interfaces with RS-232-C communication lines through a standard
25-pin D connector. The logic analyzer is compatible with RS-232-C protocol. When
a hardwire handshake method is used, the Data Terminal Ready (DTR) line, pin 20
on the connector, is used to signal if space is available for more data in the logical I/O
buffer. Pin outs of the RS-232-C connectors are listed in the following table.
RS-232-C Signal Definitions
Pin Function
Number
1 Protective Ground
2 Transmitted Data (TD)
3 Received Data (RD)
4 Request to Send (RTS)
5 Clear to Send (CTS)
6 Data Set Ready (DSR)
7 Signal Ground
8 Data Carrier Detect (DCD)
20 Data Terminal Ready (DTR)
23 Data Signal Rate Selector
8–32
RS-232-C Signal Direction and Level
Standard
AA Not applicable
BA Data from Mainframe
High = Space = "0" = +12 V
Low = Mark = "1" = –12 V
BB Data to Mainframe
High = Space = "0" = +3 V to +25 V
Low = Mark = "1" = –3 V to –25 V
CA Signal from Mainframe
High = ON = +12 V
Low = OFF = –12 V
CB Signal to Mainframe
High = ON = +3 V to +12 V
Low = OFF = –3 V to –25 V
CC Signal to Mainframe
High = ON = +3 V to +25 V
Low = OFF = –3 V to –25 V
AB Not applicable
CF Signal to Mainframe
High = ON = +3 V to +25 V
Low = OFF = –3 V to –25 V
CD Signal from Mainframe
High = ON = +12 V
Low = OFF = –12 V
CH/CI Signal from Mainframe
Always High = ON = +12 V