Product Overview

RS-232 to TTL Converter Cables
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Revision: 23-March-2013 Page 3 of 5
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TTL Connector Pin-Out and Color Scheme
 The standard TTL to RS232 cable is wired with a DB9 connector. The gender of the DB9 will be
noted in the individual item number’s description.
o On the female (plug) DB9 connector:
 Pin 2 is PC Receive data
 Pin 3 is PC Transmit data
 Pin 5 is ground
o On the male (pins) DB9 connector:
 Pin 3 is Receive Data
 Pin 2 is Transmit data
 The data signal is transmitted from the desired TTL level to RS232 levels within the electronics
embedded in the DB9 connector. The RS-232 signal can not be held high. It must be serial data
from 1200 baud to 115,000 baud.
 The data is inverted when going through the level change. This is the nature of all level changing
devices and is easily remedied by ensuring baud settings on either the TTL or PC side are set to
be inverted. Most applications already take this into account, since most data gets inverted by
level changers.
 The power must be supplied to the cable from the TTL side. The expected input voltage rangers
are 4.5V to 5.5V for MCU-016-xxx and 3V to 5.5V for MCU-026-000 items.
TTL Color code:
 BLACK Tx (TTL Output, PC Input)
 GREEN Rx (TTL Input, PC Output)
 RED Vcc (+5V)
 YELLOW Ground
 ORANGE RTS (Request to Send)
 BROWN CTS (Clear to Send
TTL Connector Descriptions
 Type 1
o Four Pin Friction Lock that carries power and signals. The Type 1 connector does not
support handshaking
 Type 2
o Two 2-Pin connectors. One connector is power and the other is data. The Type 2
connectors do not support handshaking.
 Type 3
o One Four Pin Friction Lock for data and power. One 2-Pin Connector for handshaking.