Fix Biometric Attendance Machine Not Syncing (ZKTeco & BioTime) | Step-by-Step Fix
Step-by-step fix for ZKTeco and Realtime attendance machines failing to connect or sync logs with BioTime, ZKAccess, or HR payroll software. Solve TCP port 4370, IP ping, and Comkey errors.
⚡ Direct Answer & Quick Diagnostic Summary (AEO)
To fix ZKTeco and Realtime biometric attendance terminals failing to sync employee transaction logs with BioTime, ZKAccess, or payroll software, access the terminal hardware menu and navigate to Comm. → Ethernet. Assign a dedicated static IPv4 address (e.g., 192.168.1.201), subnet 255.255.255.0, and default gateway 192.168.1.1. In Comm. → PC Connection, verify that Comm Key (Password) is set to "0" (default) and matches the device password configured in your server software. On the host computer hosting the attendance database, open Windows Defender Firewall with Advanced Security and create an inbound firewall rule allowing TCP Port 4370 (for local pull mode) and TCP Port 8081 (for ADMS cloud push protocol). You can automate this process in 30 seconds using Arbre IT's free [ZKTeco & Biometric Attendance Sync Diagnostic Utility](/downloads/). If managing multi-branch attendance across factories in Karachi, configure ADMS Cloud Server settings with your public server IP and enable real-time log push. Finally, clear flash buffer memory after manual USB backup.
Primary Root Causes
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Step-by-Step Diagnostic Checklist
Step 1: Verify Device Physical Network Configuration
On biometric terminal screen, navigate to Menu → Comm. → Ethernet. Verify IP is static (e.g. 192.168.1.201), Subnet Mask is 255.255.255.0, and Gateway matches your router (192.168.1.1). Ping the IP from the host PC.
Step 2: Reset Communication Password / Comkey
In Terminal Menu → Comm. → PC Connection, check the "Comm Key" or "Password". Ensure it is set to "0" (default). In your attendance software device settings, ensure the Device Password matches "0".
Step 3: Open Inbound TCP Port 4370 on Host PC Firewall
On the computer running BioTime / Att2008 software, open Windows Defender Firewall with Advanced Security. Create an Inbound Rule allowing TCP Port 4370 (and Web Port 8081 if using ADMS Cloud Push). Alternatively, run the [Arbre Biometric Sync Diagnostic Utility](/downloads/) to auto-detect and configure these rules.
Step 4: Configure ADMS Cloud Push Settings for Remote Branches
If attendance machine is at a remote branch/factory, go to Menu → Comm. → Cloud Server (ADMS). Enter your central server Public IP/Domain and Server Port (default 8081). Enable Push Protocol.
Step 5: Clear Stale Device Transaction Logs & DB Locks
If terminal connects but logs fail to download, purge orphaned .ldb database locks using the [Arbre Biometric Diagnostic Script](/downloads/) or go to Menu → System → Data Mgt. → Delete Attlog after taking a manual USB backup to clear corrupted record pointers in terminal flash memory.
Step 6: On-Site Biometric Repair & BioTime Configuration in Karachi
If the terminal hardware is damaged, sensor is unresponsive, or payroll database communication fails, Arbre IT offers same-day on-site technician dispatch and annual maintenance contracts (AMC) across Korangi, SITE, Clifton, DHA, and all Karachi commercial hubs (Call: +92 313 2689511).
Frequently Asked Questions
What is default communication key (Comkey) for ZKTeco devices?
The default Comm Key for all ZKTeco attendance devices is "0" (zero). If it is changed on the device, the software cannot communicate with the machine.
What network port does ZKTeco attendance machine use to download logs?
ZKTeco devices use TCP/UDP Port 4370 for local standalone communication, and TCP Port 8081 (or Port 80) for ADMS cloud push communication.
Where can I get biometric attendance machine repair and installation in Karachi?
Arbre IT provides certified on-site biometric attendance machine repair, network configuration, and BioTime/ZKAccess payroll integration across Karachi, including Korangi, SITE, Clifton, and DHA. Call +92 313 2689511 for rapid dispatch.
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