App version < 3. x:
The communication runs via the constantly open port TCP 3333, which requires a network with at least VoIP quality. "Fast Roaming" is also ideal, so that the clients can guarantee a fast switching between the access points within the network. Any disconnection of this connection will cause the port to be closed improperly and therefore cannot be opened properly again. The worst case is multiple opening of the port by the client, which ensures that more devices are displayed on the master than are actually present. The behavior remains until the client or master closes the port.
App Version > 3. x (not yet available):
Communication between the master and slave is established via an HTTP request.
This means that communication between the devices does not require a consistently stable connection. This makes it possible to build networks that do not necessarily support VoIP.
The advantage is obvious. Cheaper networks with older standards. In addition, the internal network security can work more strictly because no special port is needed.
Externally, port TCP 80 and 443 must be enabled since the data upload and the app store use these ports to download the app.
The app version 3. x is currently under development. The information is not complete or correct.
General Network Requirements:
Generally speaking, iPads/iPods prefer a transmission power of 16 to 17 dBm. Above and below it can happen that the data (packet) are sent back and forth several times until they are accepted. This in turn leads to an amount of data that interferes with network performance. No other device can send data during this time.
The roaming behavior is special and can cause a fixed device (master) to switch back and forth between several access points. This can result in the mobile devices losing the connection to the master.
The master's "jumping" can also be suppressed by giving the master its own SSID, which transmits either on 2.4 or 5 GHz. A preference of 5 GHz rarely helps, unique SSID's per band are better.
Encryption:
We recommend that you use WPA2 as encryption. WEP is no longer up-to-date and WPA causes certain problems with iOS. Even if not officially confirmed, the performance of iOS with WPA2-AES is the best.
A mixed mode (WPA/WPA2) can only be used if the devices in the network are not equipped with WPA2.
Frequency/Channel:
A channel width of 20 MHz, instead of the usual 40 MHz or 80 MHz in 5 GHz band, has a positive effect on the performance. The more other WLAN devices are nearby, the less time your router/access point has to send the data. This means that the access point manages less within a narrower band. Every WiFi with a shared frequency has the right to send data. During this time, no other device can transmit data, which means that it takes longer to send data and can fail if the connection is poor.
For security reasons, it is strongly recommended that the POS-System works in its own seperate network. Even if the data is transmitted in encrypted form, disturbances caused by clients that do not belong to the POS-System can be avoided.
Summary:
- WPA2 as standard encryption
- Separate SSIDs for 2.4 and 5 GHz, network-wide transmission power optimally on 16/17 dBm
- Optimal way for the master is to have its own SSID which is only broadcasted via one AP channel bandwidth 20 MHz
- Distribution of the channels according to IEEE 802.11b 1,7,13 or IEEE 802.11g/n 1,5,9,13
- Fast Roaming/Beam Forming IEEE 802.11k/r/v
- Out/In Port TCP 80 and 443
- Worst reception -65 dBm