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Catalog # 305123 - Model 4123 DB25 Auto Sensing A/B Switch

    DB25 Auto Sensing A/B SwitchDB25 Auto Sensing A/B SwitchDB25 Auto Sensing A/B SwitchDB25 Auto Sensing A/B Switch
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    • DB25 Auto Sensing A/B Switch
    • DB25 Auto Sensing A/B Switch
    • DB25 Auto Sensing A/B Switch
    • DB25 Auto Sensing A/B Switch
Base Price:
Catalog No: 305123
Model No: 4123
Product Type:Switches: Copper
Cable Type/Port Connector:DB25 Switch Ports
Channels per Switch Chassis:1
Electronic Switches/Power Required:PathWay® Copper
Remote Control:Auto Fallback, RS232 Serial
Auto Fallback:AutoSense, Data Monitor Port A & Port B
Pins Switched:25
Remote Port:DB9
Local Control:Pushbutton

  • Auto Sensing on ports A and B.
  • Automatic switching based on RS232 TD activity.  
  • DB9 RS232 Serial Remote Control.

Shipping Terms

Shipments are made via UPS Ground, unless otherwise specified. Freight charges are prepaid and added to your invoice. We can estimate the freight costs for you.

We can ship freight collect on your account, just provide your UPS Account Number.

We can also ship via the carrier of your choice. Provide the details and your account number.

Products shall be shipped F.O.B. Electro Standards' facility. Title to and risk of loss or damage to the products shall pass to you upon Electro Standards delivery of the products to a carrier for shipment. Title to software will remain with the applicable licensor. Electro Standards' prices do not include shipping and handling charges. Electro Standards reserves the right to use its own discretion in the manner and routing of shipments. Electro Standards shall be permitted to deliver products in separate lots.

Shipping Return Policy

  • To return an item, contact Electro Standards at 401-943-1164 to obtain a Return Material Authorization (RMA) number. RMA numbers are valid for 30 days after the date of the shipment and cannot be extended or re-issued. We are unable to accept returns without an RMA number.
  • All returns except those of defective product are subject to a 15% restocking fee, and additional charges for handling or freight are refunded only in cases of defective products.
  • Return freight must be shipped prepaid. We recommend that you insure the package as you are responsible for risk of loss on all returned packages. We recommend that all cartons are properly packed as Electro Standards is not responsible for product damaged en route. We do not issue call tags for product returns.
  • Returned product must be clean, undamaged, and complete with all manuals, accessories, documents and packaging. The items must be in a resalable condition.
  • The product must have with it a copy of the original invoice or packing slip and the appropriate RMA paperwork.
  • If your item is not working properly, please contact Electro Standards at 401-943-1164 for help in trouble-shooting your application.
  • If the product is defective, Electro Standards will repair or replace that item (at our discretion) upon receipt and evaluation of the original product.
  • Electro Standards reserves the right to authorize product returns after 30 days from the invoice date in some cases. If the product is accepted after 30 days, credit will be issued toward future pruchases only and some additional restocking charges may be applied.
  • All credits from RMAs must be used within one calendar year of issue.

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PathWay® Model 4123 DB25 Automatic Fallback A/B Switch with RS232 Remote

  • Smart Data Switch Automatically Switches to the Port with Valid Activity!

  • Automatically Switches between Backup and Primary Link

  • Auto Sensing on Ports A and B.


  • DATA CONNECTORS: (3) DB25 female connectors labeled A, B, and COMMON on the rear panel.
  • FRONT PANEL CONTROL: (1) Manual pushbutton allows local switching or to override Automatic Fallback Mode to Manual Mode.
  • DISPLAY: (2) Front panel LEDs display present position, power status and operating mode.
  • REMOTE CONTROL: (1) DB9 female connector on rear panel accepts ASCII RS232 Serial Data for Remote Control operation.
  • POWER: UL approved 100VAC-240VAC 50 Hz/60Hz wall mount power module supplies 12VDC, 625mA to the unit. Has 2-prong, US, non-polarized plug.
  • DIMENSIONS: Desktop configuration 8.12" W x 2.43" H x 7.01" D (20.7 x 6.2 x 20.9 cm)
  • WEIGHT:Approximately 1.9 lbs. (0.9 kg)

PathWay® Model 4123 DB25 Automatic Fallback A/B Switch Application.

DB25 Automatic Fallback A/B Application (Automatic Protection Application);  A COMMON Device is connected to the DB25 COMMON port with access to a Primary Line A and a Backup Line B connected to the DB25 A and B ports. The data activity is monitored on both ports A and B. The unit auto senses valid activity on both A and B ports. (Auto Sense on Ports A and B) The DB9 RS232 Remote allows a user to control the unit remotely via RS232 ASCII commands.

  • Auto Sensing on ports A and B.
  • Automatic switching based on RS232 TD activity.  
  • DB9 RS232 Serial Remote Control.

PathWay® Model 4123 DB25 Auto Fallback application


  • Great for Automatic Protection Application
  • The switch ports are transparent to all data.
  • All (25) pins of the DB25 interface are switched via break-before-make electromechanical relays.
  • The unit maintains last set position on power loss and continues to pass data.
  • Front panel pushbutton control.
  • Remote RS232 ASCII commands that allow the user to; control switch position, lockout front panel operations, change modes, obtain switch status, query firmware version number, query serial number, as well as, toggle Signal Loss Mode, query Fallback Mode, and enable/disable autosend of switch positions.
  • Automatic switching based on RS232 TD activity.  
  • Front panel LED's display present position, power status, and operating mode.
  • Attractive all metal black box packaging provides EMI/RFI shielding.
  • Custom length DB25 cables available for your switch installation.
  • Municipalities, schools, government: This product is on GSA Schedule!

The PathWay® Model 4123 DB25 Automatic Fallback A/B Switch with RS232 Remote allows the user the capability of sharing a single port interface device connected to the "COMMON" port among two other devices connected to the "A" and "B, ports with remote access functionality.  The Model 4123 is packaged in a slim desktop style enclosure.

The switch may be controlled locally by manually operating the front panel pushbutton, or remotely through the DB9 Female Serial Interface Remote port located on the rear of the unit. The front panel LED display indicates the switch position, and unit power status, and mode of operation.

The unit monitors data activity on both port "A" and "B". If activity on the connected port is lost, and if the other port has established valid activity, the unit automatically switches to the port with activity. As long as there is activity on the present port, the unit will maintain the connection with the connected port. If neither port has activity, it will stay connected to the present port and continue to monitor for active data on both ports to switch to.


(Cat No 517277) CE, RoHS, and UL listed table mount power module, 100 VAC / 240 VAC, 50Hz/60Hz for use in place of standard power module that is included with the unit. Has IEC 60320 C14 inlet.  Ideal for international applications.

This high-quality network switch is available to city, state, and federal government purchasers at a discounted price and favorable payment and shipping terms via GSA Schedule GS-35F-0286V. Click here for GSA details.

Model 4123 Single Channel RS232 A/B Switch,  DB25 A/B Autosense unit is available to government purchasers on our GSA Schedule GS-35F-0286V. Call for discounted price and terms.

Electro Standards can supply all your Network Cable requirements. Click here to reach our CABLES, COPPER NETWORK Webpage.

For custom network switches call our friendly customer support staff at 401-943-1164, email eslab@electrostandards.com, or complete our online form: /Products-Custom/Copper-Switch/

All data switches, data communication products, and data acquisition products are subject to a one year warranty against manufacturing defects.  The limit of ESL liability is limited to the cost of the ESL product provided.

*Prices online are subject to change and verification.

All ESL products are available for export.

Electro Standards welcomes International inquiries: commutateur d'ordinateur,  equipo interruptor, interruttore del calcolatore, interruptor do computador, dator switch.

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