Question 1

Install fails or rolls back?

Accepted Answer

Disconnect the T4 C, run the ZK driver installer as Administrator, and temporarily disable antivirus. If an older ZK/USB-serial driver exists, uninstall it in Device Manager (enable “Show hidden devices”), reboot, then reinstall the correct 32/64-bit package.

Question 2

Device not detected?

Accepted Answer

Use a direct rear USB port and the supplied cable; avoid hubs. Power-cycle the T4 C, check Device Manager for an unknown/USB-serial device, and confirm the terminal is in communication mode, not standby.

Question 3

Version or COM-port conflicts?

Accepted Answer

Remove stale ZK drivers and old COM ports, reboot, and let Windows assign a new port. In the attendance software, reselect the T4 C’s current COM port and matching baud rate; don’t open two ZK utilities on the same port.

ZK Software T4 C Driver