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Catalog # 535049 - Model 4126 DB9 Automatic Fallback A/B Switch, RS232 Remote

    DB9 Automatic Fallback A/B SwitchDB9 Automatic Fallback A/B SwitchDB9 Automatic Fallback A/B SwitchDB9 Automatic Fallback A/B Switch
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    • DB9 Automatic Fallback A/B Switch
    • DB9 Automatic Fallback A/B Switch
    • DB9 Automatic Fallback A/B Switch
    • DB9 Automatic Fallback A/B Switch
Base Price:
Catalog No: 535049
Model No: 4126
Product Type:Switches: Copper
Cable Type/Port Connector:DB9 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:9
Remote Port:DB9
Local Control:Pushbutton

  • DB9 Automatic Fallback A/B Switch with 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.

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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 4126 DB9 Automatic Fallback A/B Switch with RS232 Remote

  • Smart Data Switch Automatically Selects the Port with Valid Activity!

  • Automatically Switches between Backup and Primary Link


  • DATA CONNECTORS: A, B, and COMMON are DB9(F) located 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 2.37" H x 7.31" D (20.7 x 6.1 x 18.6 cm)
  • WEIGHT:Approximately 1.7 lbs. (0.8 kg)

PathWay® Model 4126 DB9 Automatic Fallback A/B Switch Application.

DB9 Automatic Fallback A/B Application (Activity Sense for Auto Switch); A COMMON Device is connected to the DB9 COMMON port with access to a Primary Line A and a Backup Line B connected to the DB9 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.PathWay® Model 4126 DB9 Automatic Fallback A/B Switch Application


  • The switch ports are transparent to all data.
  • All (9) pins of the DB9 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 (In manual mode).
  • Remote RS232 ASCII commands that allow the user to control switch position, lockout front panel operations, change modes, obtain switch status, as well as query firmware version number, query serial number and enable/disable auto-send of switch positions.
  • In Manual Mode, the unit does not switch between A and B, unless commanded to do so via the front panel pushbutton or remote commands.
  • In Auto Fallback Mode, automatically chooses its switch position based on signal presence.
  • Signal Presence based on RS232 TD activity on pin 3 of ports A and B.
  • Two signal loss modes and eight delay time are settable via the Remote RS232 commands only.
  • Delay time selections are in one second increments from 1 second to 8 seconds.
  • Signal loss modes either Alternate or Maintain position on signal loss (only in automatic fallback mode).
  • Default settings are: Auto, Maintain, 2 second delay.
  • Front panel LED’s display present position and power status and operating mode.

The PathWay® Model 4126 DB9 Automatic Fallback A/B Switch with RS-232 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 4126 is packaged in a slim desktop style enclosure.

The switch may be controlled locally by manually operating the front panel push button or remotely from 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.

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

PathWay® is a registered trademark of Electro Standards Laboratories.

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/

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

All ESL products are available for export. Electro Standards welcomes business from International companies: commutateur de réseau, conmutador de red, switch di rete, przelacznik sieciowy , switch de rede, nätverksswitch.

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.

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