Q232-STS
RS-232 Serial Transfer Switch User Manual
User Manual
Overview
The QuEST Q232 Serial Transfer Switch transfers RS232 signals from a primary communications link to a
backup communications link. Designed for railway
applications, the Q232-STS meets the demanding
environmental requirements of Class C wayside
signal equipment.
The Q232-STS is packaged in a low-profile rugged
plastic case with ears for wall mounting.
Power is connected to a two-wire removable plug
connector. The serial data connectors are DB9 male
for the primary and backup links and DB9 female for
the interlocking controller connection.
The Q232-STS will transfer to the backup link when
the backup communications equipment asserts its
DCD signal and transmits data. When the backup
link de-asserts its DCD signal, the Q232-STS will
switch back to the primary link.
Product Features
• 10 – 32 VDC Input Voltage Range
• 2,000 Vrms isolation
• -40 to 70° C Operating Range
• Supports data rates up to 57,600 bps
• Transfers from primary to backup link when
Backup DCD and RXD signals are active
• Status and data activity LEDs
Specifications
Serial Ports
Primary Port DB9 M (RXD, TXD, RTS, DCD, and
COM)
Backup Port DB9 M (RXD, TXD, RTS, DCD, and
COM)
Controller Port DB9 F (RXD, TXD, RTS, CTS, DCD,
and COM) CTS connected to RTS
Data Rate Up to 57,600 bps
Isolation 2,000 Vrms (60 Hz, 3 mA maximum
leakage for 60 s)
Note: No isolation between primary
and backup ports.
Power Input
Power Connector 2-position removable terminal block
Wire Size 22 to 14 AWG
Input Voltage 10 to 32 VDC
Power Consumption 0.7 W (12 VDC), 1.9 W (32 VDC)
Fuse 2 A
Reverse Polarity
Protection
Indicators
Power Green LED
RS-232 Signals Yellow LEDs
Link Active Blue LEDs
Mechanical
Dimensions 7.285 x 4.72 x 1.25 in.
Case Material Flame retardant ABS
Environmental (AREMA Class C Compliant)
Operating Temperature -40 to 70° C
Operating Humidity 0 to 95% non-condensing
Yes
Ordering Information
PN: 800-160140-0001
Email PO to: orders@questrail.com
095-160140-1000, Rev. A00 © QuEST Rail LLC 2018 1
Q232-STS
RS-232 Serial Transfer Switch User Manual
Typical Application
Serial Port Pinout
Battery
RS-232
Radio Modem
Interlocking
Controller
Primary Port
Signal Pin (DB9 M)
TXD 3
RXD 2
RTS 7
DCD 1
COM 5
Backup Port
Signal Pin (DB9 M)
TXD 3
RXD 2
RTS 7
DCD 1
COM 5
Controller Port
Signal Pin (DB9 F)
TXD 3
RXD 2
RTS 7
CTS 8 (Internally connected to RTS)
DCD 1
COM 5
Galvanic Isolation
The Q232-STS provides 2,000 Vrms isolation
between the following circuits:
• Battery Input
• Controller Interface
• Primary and Backup Links
Operation
When the Backup Port DCD signal is deasserted, all communication signals are routed
between the Primary Port and Controller Port.
When the Backup Port DCD signal is asserted
and data is received on the Backup Port, all
communication signals are routed between the
Backup Port and Controller Port.
LEDs provide status for input power, RS-232
signals, and active link.
095-160140-1000, Rev. A00 © QuEST Rail LLC 2018 2
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