Anti-passback is a security mechanism that prevents a person from passing back her access card to the next person. It is designed to prevent the next person from verifying herself with another person's access card. When using BioStar, you can set up an Anti-passback zone, which requires users who've already entered an area to leave the zone first before entering the area again. For instance, if the zone consists of two devices (let's call them Device A and Device B here), the user who's been already verified on Device A must verify herself on Device B before verifying herself on Device A again. 

You can set up an anti-passback zone by performing the following steps: 

1. On the Doors page, click Add New Zone. 

2. Enter a name for the Anti-passback zone and choose Anti-passback Zone from the Type drop-down list. 

3. Configure the settings of the Anti-passback zone and add devices to the zone by clicking Add Device. 

• APB Type 
  - Soft: A user who has broken the Anti-passback rule can enter the area without the administrator explicitly releasing the alarm. 
  - Hard: A user who has broken the Anti-passback rule can't enter the area without the administrator explicitly releasing the alarm.
• In case of Disconnected 
  - Door Open: Doors in the zone will get opened when the communication between the master and member devices is disconnected. 
  - Door Close: Doors in the zone will get closed when the communication between the master and member devices is disconnected.

4. Choose the devices you want to add to the zone as In Device and click the right arrow button. Perform the same for Out Device.

5. Click Apply to transfer the settings to the devices.