401-943-1164 / US & Canada Toll Free: 877-943-1164

Catalog # 304209 - Model 4209 DB25 Automatic Fallback A/B Switch with Telnet Remote

    SB25 Automatic Fallback A/B SwitchSB25 Automatic Fallback A/B SwitchSB25 Automatic Fallback A/B Switch
Click image to enlarge
    • SB25 Automatic Fallback A/B Switch
    • SB25 Automatic Fallback A/B Switch
    • SB25 Automatic Fallback A/B Switch
Base Price:
Catalog No: 304209
Model No: 4209
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, Ethernet
Auto Fallback:AutoSense, Monitors Port B, RTS Active
Pins Switched:25
Remote Port:RJ45
Local Control:Pushbutton


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.

Ask a Question

Protected Document Request



PathWay® Model 4209 DB25 Automatic Fallback Switch with Telnet Remote

  • Automatic Fallback Mode or Manual Mode


  • PORT CONNECTORS: (3) DB25 female connectors labeled A, B, and COMMON.
  • FRONT PANEL CONTROL: (3) Manual pushbuttons; (1) Positional, (1) Manual Mode, and (1) Automatic Fallback Mode).
  • DISPLAY: (4) LED's;(2) Positional Green LED's, (1) Blue LED (Auto Fallback Mode), (1) Blue LED (Manual Mode)
  • REMOTE CONTROL: (1) RJ45 female connector on rear panel accepts 10/100 Base-T LAN Access Ethernet that uses TELNET commands for Remote Control operation.
  • POWER: UL approved 100VAC/240VAC 50 Hz/60Hz wall mount power module supplies 12VDC, 500 mA to the unit.
  • DIMENSIONS: Desktop configuration 8.11" W x 2.42" H x 7.30" D (20.6 x 6.2 x 18.6 cm)
  • WEIGHT: Approximately 2.0 lbs. (0.9 kg)

PathWay® Model 4209 DB25 Automatic Fallback Switch with Telnet Remote:

The drawing illustrates a COMMON Device connected to the DB25 COMMON port with access to a Primary Line connected to Port A and a Secondary Line connected to Port B. The unit monitors Port B for data activity. The Remote RJ45 10/100Base-T LAN Ethernet port can be used to remotely control the unit via Telnet Commands and is IP Addressable!  

  • Activity on Port B = B position;
  • No activity on Port B = A position
  • Auto Sense to automatically change position based on presence or absence of signal on Port B.
Network Diagram of Model 4209 Fallbaock Application



  • The switch ports are transparent to data.
  • All (25) pins of the DB25 interface are switched via break-before-make electromechanical relays.
  • Pins 4 and 19 of the B port are monitored for RTS being active.
  • The unit maintains last set position on power loss and continues to pass data.
  • Front panel pushbutton control.
  • Automatic fallback mode and manual mode.
  • Control of the switch position from a 10/100Base-T LAN Ethernet environment.
  • Remote Control Telnet command interface that allows the user to control switch position, lockout front panel operations, toggle between automatic and manual modes, obtain switch status, as well as, query firmware version number, query serial number and enable/disable autosend of switch positions.
  • Front panel LED's display the present position and power status.
  • The unit automatically switches to the B position, when data is detected on port B.
  • Unit chassis ground is connected to the signal ground.
  • Attractive all metal black box packaging provides EMI/RFI shielding.
  • Custom length DB25 cables available for your switch installation.

The PathWay® Model 4209 DB25 A/B Automatic Fallback Switch with Telnet Remote allows the user the capability of sharing a single DB25 interface device connected to the Common port among two other devices connected to the A and B ports. The Model 4209 is packaged in a slim desktop style enclosure.

The switch may be controlled manually via front panel pushbutton, or Remote Control. Remote access can be accomplished using an Ethernet 10/100Base-T connection and Telnet commands.  The front panel LED display indicates the switch position, and power status.

The unit monitors data activity on port "B". If the unit is in the A position and data activity is present on port B, the unit automatically switches to the B position. The unit will then remain in the B position until signal is not present, in which the unit will switch back to the A position automatically.

Wide Range Power Option Available: (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.

 All data switch boxes, 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.


Available Combo Deals