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

Catalog # 304133 - Model 4133 DB25 A/B Automatic Fallback Switch

    DB25 A/B Automatic Fallback SwitchDB25 A/B Automatic Fallback SwitchDB25 A/B Automatic Fallback SwitchDB25 A/B Automatic Fallback Switch
Click image to enlarge
    • DB25 A/B Automatic Fallback Switch
    • DB25 A/B Automatic Fallback Switch
    • DB25 A/B Automatic Fallback Switch
    • DB25 A/B Automatic Fallback Switch
Base Price:
Catalog No: 304133
Model No: 4133
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, Contact Closure, RS232 Serial
Auto Fallback:AutoSense, Data Monitor Port A, TD & RD Activity
Pins Switched:25
Remote Port:DB9
Local Control:Pushbutton
Protocol:loss of data on port A


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


Model 4133 DB25 Single Channel A/B Automatic Fallback Switch with RS232 Remote Control

  • Automatically switches to Backup Line when Primary Line Fails.


  • PORT CONNECTORS: (3) DB25 female connectors labeled A, B, and COMMON.
  • FRONT PANEL CONTROL: (1) Manual pushbutton to select switch position and mode of operation to be changed.
  • REMOTE CONTROL: (1) DB9(F) connector labeled REMOTE accepts RS232 Serial Data ASCII commands.
  • DISPLAY: (2) Red LED's display switch position, and switch mode.
  • POWER: UL approved 100VAC/240VAC, 50Hz/60Hz wall mount power module supplies 12VDC, 500mA to the unit. Has 2-prong, US, non-polarized plug.
  • DIMENSIONS: 8.10" W x 2.41" H x 7.30" D (20.6 x 6.2 x 18.6 cm).
  • WEIGHT: Approximately 1.9 lbs. (0.9 kg)


The drawing illustrates a single channel of DB25 switching. A COMMON device connected to the DB25 COMMON port has access two other devices connected to the DB25 Port A (PRIMARY LINE), and the DB25 Port B (BACKUP LINE). The switch monitors activity on the PRIMARY LINE (port A). Once activity is lost, the unit switches to the BACKUP LINE (Port B). The user can override the automatic fallback operation via the front panel push button or using ASCII Commands via the DB9 REMOTE port.

PathWay® Model 4133 Auto Fallback Application drawing


  • Ideal for fallback applications.
  • 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 the switch position, lockout front panel operations, change the fallback mode, set the delay time, select pins monitored, change the recovery mode, and obtain switch status, as well as query firmware version, serial number, and enable/disable autosend of switch positions.
  • REMOTE port contact closure status on pins, 6, 7, and 8 provide dry contact logic to obtain present switch position.
  • Automatic switching based on RS232 TD and/or RD activity on Port A, with monitored signals selectable by RS232 commands.
  • Recovery Mode can be set to either Automatic or Manual.
  • Front panel LED's display present position, switch mode, and power status.

The PathWay® Model 4133 Single Channel DB25 Auto Fallback Switch with RS232 Remote Control 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 4133 is packaged in a slim desktop style enclosure.

The switch may be controlled locally by manually operating the front panel pushbutton 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, switch mode, and power status.

The unit monitors data activity on port "A". If the unit is in the A position and activity is lost for the duration of the set delay time, the unit automatically switches to the B position.  Depending on the Recovery Mode set, the unit will then either remain in the B position until commanded to switch to A position by the pushbutton or Remote, and switch back to A automatically when the signal returns.

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

Custom Network Switches are available. Contact us by phone, email, or complete the Online Custom Product Request  Form.

Electro Standards can supply all of 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.

 *Prices online are subject to change and verification.

Available Combo Deals