User's Manual

TS4000 Radio Modem User’s Manual Appendix A - Serial Ports 50
amperage limitation of the flex circuit connecting the LEMO connector to the
modem board.
[6] These are the wire colors of the internal wires for the standard cable provided
with the watertight version of the TS4000.
Signal Connector Pinout Direction
Signal Name Mnemonic 9 Pin 25 Pin DCE DTE
Signal Ground SG 5 1, 7 -- --
Transmit Data TD 3 2 Input Output
Receive Data RD 2 3 Output Input
Request to Send RTS 7 4 Input Output
Clear to Send CTS 8 5 Output Input
Data Carrier Detect DCD 1 8 Output Input
Ring Indicator RI 9 22 Output Input
Data Set Ready DSR 6 6 Output Input
Data Terminal Ready DTR 4 20 Input Output
Signal Description
Request to Send (RTS) Request for transmission from the DTE.
Clear to Send (CTS) Response (to the Request to Send) from the DCE
indicating a readiness to transmit data.
Data Carrier Detect (DCD) Status from the DCE indicating that it is receiving.
Ring Indicator (RI) Status from the DCE indicating that it has detected
the ring state.
Data Set Ready (DSR) Status from the DCE indicating that it is
operational.
Data Terminal Ready (DTR) Status from the DTE indicating that it is
operational.
Serial port 1 can be configured for either RS-232 or TTL signal levels. The signal
level selection is controlled with internal jumper plugs (see Appendix F - Internal
Jumper Block).
The RS-232 standard defines minimum and maximum voltage levels for the
drivers and receivers. However, in practice the drivers and receivers work
correctly with signal levels that are different from the specification.
Level (volts DC)
Type Low High
Drivers (into a 3k to 7k ohm load)
RS-232 Specification
Actual TS4000 Drive Levels
-15 to -5
-9 to -6
+5 to +15
+6 to +9
Receivers (with 3k to 7k ohm load)
RS-232 Specification
Actual TS4000 Receive Levels
-25 to -3
-25 to +0.8
+3 to +25
+2.4 to +25
Standard RS-232
Serial Port Pinout
Standard Usage of
the RS-232 Control
Signals
Signal Levels
RS-232 Signal Levels