Unstable operation of point-of-sale equipment when using USB hubs without power

Instructions for cases when printers, scanners, scales, or bank terminals work unstably due to connection through passive USB hubs (without external power).

Passive USB hubs without external power often become the cause of unstable operation of retail equipment in Torgsoft. If several devices are connected to one hub, they may lack power or USB connection stability, causing printers, scanners, scales, or bank terminals to disappear from Windows, freeze, or work only from time to time.

When to check the USB hub and power supply

• several retail devices are connected to one USB hub;

• the equipment operates on a laptop or all-in-one PC with a limited number of USB ports;

• USB ports on the front panel of the PC are used;

• long USB cables or extension cables are used;

• the equipment worked stably, but started disconnecting without any settings being changed.

When to check the USB hub and power supply

• the device periodically appears and disappears in Windows;

• Unknown Device appears in Device Manager;

• the equipment works only when directly connected to the PC;

• the printer starts printing and stops;

• the scanner beeps, but does not send data to the program;

• when one device is operating, another suddenly disconnects;

• the bank terminal does not return a payment response to the program.

Why a passive USB hub causes failures

USB current limitations

One USB 2.0 port provides up to 500 mA. At the moment of initialization or during active operation, retail devices may consume more than a standard port allows.

Passive USB hub

A passive hub shares the power of one USB port among all connected devices. As a result, voltage drops and unstable operation occur.

Powering the interface board

Even equipment with its own power supply (220 V) often powers the USB interface from the computer, not from the mains.

Cable losses

Long USB cables, extension cables, and front-panel PC ports create additional resistance and reduce voltage.

USB controller restart

A failure of one device can trigger a restart of the entire USB branch, which leads to the disconnection of other devices.

How to restore stable equipment operation

Step 1. Connect critical equipment directly

Connect bank terminals, fiscal registrars, license keys, and scales directly to the USB ports on the rear panel of the motherboard.

Step 2. Replace the passive USB hub

For multiple devices, use an active USB hub with its own power supply unit (220 V).

Step 3. Check the cables

• the maximum recommended USB cable length is 1.8 m;

• for longer distances, use active USB extenders (repeaters);

• avoid cheap or thin cables.

Step 4. Disable USB power saving in Windows

1. Open Device Manager.

2. Open the USB Controllers section.
   For each USB Root Hub / Generic USB Hub:

• Properties → Power Management.

• Clear the checkbox «Allow the computer to turn off this device to save power».

How to check the result

• there are no errors or disappearing devices in Device Manager;

• during simultaneous printing and scanning, devices do not disconnect;

• the bank terminal consistently returns a payment response;

• the equipment does not disappear after idle time or under load.

How to avoid repeated USB connection problems

• do not use passive USB hubs at retail locations;

• connect equipment to the rear ports of the motherboard;

• avoid long USB cables without active amplification;

• disable USB power saving on checkout PCs immediately.

What is important to remember

If retail equipment works unstably and is connected through a USB hub without power, the hub must be replaced with an active one or the device must be connected directly to the PC.