P#9156R1_232PTC9-0812 - 1/2
2003 by B&B Electronics. All rights reserved.
Model: 232PTC9
RS-232 Two-Port Combiner
Introduction
B&B Electronics Model 232PTC9 permits two or more serial devices to share a serial port on a host computer. When
one of the devices on either of the slave ports transmits data, it captures the data path to the master port and locks out
the other slave port. When data transmission is finished, either slave port gets access to the master port by being the
first to start sending data. The RTS line can also be used to control data flow to the master port.
The 232PTC9 can be cascaded to combine as many devices as needed into one host port. A typical application would
be to share one host port with several terminals, scanners, scales, or other devices that only need access to the host
port occasionally as shown in Figure 1.
Host
TD RTS
RD
5 3
2 7
Computer
Master
Port
Port 1 Port 2
Master
Port
TD TD
3 3
Slave Slave
Port 2 Port 1 RD RD
2 2
232PTC9
Control
Circuitry
RTS RTS
7 7
CTS CTS
8 8
Ground
5 5-
Bar Code
Scanner
Figure 2. 232PTC9 Port Diagram
Terminal
Figure 1. Application Example
Operation
Data flow from master port to slave ports
All data that is sent to the TX line, pin 3 on the master port, is broadcast to both slave ports under all conditions. This
data appears on pin 2 of each slave port.
Data flow from slave ports to master port
Data that is sent to the TX line (pin 3) on the slave ports must compete for the path to the master port. There are two
methods of capturing the path to the master port, RTS and automatic data sensing. The first slave port to either raise
its RTS line or transmit data captures the path to the master port. The path will be locked on that slave port until it either
lowers its RTS line, or 60 milliseconds after the end of its transmission. Note that the 232PTC does not buffer any data,
any data sent to the opposite slave port during this period will be lost.
www.bb-elec.com orders@bb-elec.com support@bb-elec.com
International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104
European Office: Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445
PRODUCT INFORMATION B&B ELECTRONICS
P#9156R1_232PTC9-0812 - 2/2
2003 by B&B Electronics. All rights reserved.
Handshake signals
The CTS signal on each slave port indicates to the slave devices if the path to the master port is available. If the slave
ports CTS line is high, data received by that port will be transmitted out the master port. If CTS is low, the opposite
slave port has captured the path to the master and any data at the inactive slave port will be lost. For example, if both
slave ports are inactive and have RTS low, CTS will be high at both slave ports, indicating that the path is available. As
soon as one slave port captures the path by either beginning its transmission or raising its RTS line, the CTS signal at
the opposite slave port will drop to the low state. The RTS output on the pin 7 of the master port follows the RTS signal
level found on the active slave port.
Pinouts
All ports on the 232PTC are configured as RS-232 DCE ports, using DB9 female connectors. Note that a null-modem
type connection will be required to connect the 232PTC9 to other DCE configured ports. Tables 1 and 2 and Figure 2
show the configuration of each port.
TD 3 Input TD 3 Input
RD 2 Output RD 2 Output
RTS 7 Output RTS 7 Input
GND 5 -------- CTS 8 Output
GND 5 --------
Cascading Port Combiners
Port combiners can be cascaded by connecting the master port of each successive unit to one of the slave ports of the
preceding unit. Each additional port combiner adds one slave port to the system.
Specifications
Dimensions: 4.01 x 2.00 x 0.9 in (10.19 x 5.08 x 2.29 cm)
Connectors: (3) DB-9 female, RS-232 DCE configuration
Power Supply (required): 12-17VDC (B&B model # 232PS recommended; sold separately)
Current Draw: 95 mA
Operating Temp: 0-50 C (32-122 F)
Signals: TD, RD, RTS (slave to master only)
CTS indicates open channel (slave only)
DECLARATION OF CONFORMITY
Manufacturers Name: B&B Electronics Manufacturing Company
Manufacturers Address: P.O. Box 1040
707 Dayton Road
Ottawa, IL 61350 USA
Model Numbers: 232PTC9
Description: RS-232 Two-Port Combiner
Type: Light industrial ITE equipment
Application of Council Directive: 89/336/EEC
Standards: EN 55022
EN 61000-6-1
EN 61000 (-4-2, -4-3, -4-4, -4-5, -4-6, -4-8, -4-11)
Robert M. Paratore, Director of Engineering
www.bb-elec.com orders@bb-elec.com support@bb-elec.com
International Office: 707 Dayton Road PO Box 1040 Ottawa, IL 61350 USA 815-433-5100 Fax 433-5104
European Office: Westlink Commercial Park Oranmore Co. Galway Ireland +353 91 792444 Fax +353 91 792445
PRODUCT INFORMATION B&B ELECTRONICS