A simple RF field can be established with a single access point (infrastructure mode). The access point provides at least one Industrial Ethernet interface for connection to the wired network. Nodes, such as mobile controllers or a Field PG can move freely within the RF field and exchange data with other nodes via this access point.

If the RF field of a single access point (wireless cell) is insufficient, it can be expanded by further access points. The individual wireless cells must overlap so that moving nodes can be handed over seamlessly from one access point to the next (roaming). This is transparent for the application. The access points must be able to exchange data via Industrial Ethernet or a Wireless Distribution System (WDS).

If the access points are not connected to Industrial Ethernet using a wired connection (e.g. no cable tray available for a data line), the "Wireless Distribution System" mode must be selected. An access point from the SCALANCE W700 product line can communicate via WDS with several other access points that are not connected to the data network by a direct wired connection. Remote directional antennas can be used to achieve ranges of several thousand meters outdoors.

Apart from a reliable radio link, the SCALANCE W700 Access Points are characterized by their support of IT mechanisms:

• IEEE 802.11a/b/g/n for different frequency ranges
• IEEE 802.11e for Wireless Multimedia (WMM)
• IEEE 802.11i for security
• Construction of redundant networks with the Spanning Tree Protocols (RSTP, MSTP)
• Virtual networks (VLAN) for example to logically separate different user groups
• Sending the log entries of the SCALANCE W devices to a Syslog server
• Modern security mechanisms (e.g. network security such as IEEE 802.1x, RADIUS, EAP mechanisms)

Security

A high degree of data security is achieved by means of the WPA2/IEEE 802.11i mechanisms. These define modern procedures that control a regular exchange of the complete 128-bit key as well as performing the access check (authentication) of a node. The Advanced Encryption Standard (AES) is available for data encryption.

On top of this, access to the devices (HTTPS) is encrypted and a secure logon (SSH) is possible. If a security concept in combination with SCALANCE S is required, the security requirements can be increased using Virtual Private Networks (VPN).

iFeatures (only in conjunction with KEY-PLUG)

iPCF (industrial Point Coordination Function):
The iPCF mode is a good choice for applications with requirements for real-time and predictable response times (deterministic response), even when mobile nodes are roaming from one access point to the next. This ensures that wireless PROFINET IO is supported and that safety-related signals, e.g. emergency stop, can be linked into the RF field. This means that even video signals from mobile nodes can be transmitted with a high level of quality. The iPCF mechanism expands the IEEE 802.11 standard and must be available on both the client module and the access point. In an RF field in which iPCF is used, no IEEE 802.11-compliant nodes can be operated.

iPCF is recommended for applications where wireless network nodes move along predefined paths (e.g. suspended monorail). RCoax radiating cables or directional antennas must be used for this purpose.

Linking in an automated guided vehicle system using iPCF with the SCALANCE W774-1 RJ45 and KEY-PLUG

iPCF-MC (iPCF Management Channel) ¹⁾:
iPCF-MC is available as a further development of iPCF. This mode should be used if IWLAN stations that also support iPCF-MC move freely about in the coverage area (especially when using omni-directional antennas) and are to exchange data deterministically. This functionality can only be achieved in connection with access points with two wireless interfaces and the KEY PLUG.

iREF (industrial Range Extension Function):
The range of an individual access point is very important, e.g. for path-based applications. Using iREF, it is now possible to align the various antennas of a wireless interface in different directions. This allows a longer path or a greater area to be covered using a single access point, which reduces the number of channels used and the number of access points.

Note:
These iFeatures cannot be used in parallel.

Diagnostics and management

• Web-based (HTTP/HTTPS) management tool for configuration and diagnostics using a standard browser
• LEDs for signaling operating status and fault/error states
• Signaling of faults by means of SNMP trap or e-mail to a network management tool
• Configuration and diagnostics using Web based Management, Command Line Interface, and SNMP. Devices and networks can be configured using STEP 7 (TIA Portal). For cyclic monitoring, diagnostics and documentation (reporting) in network mode, the SINEMA Server software is recommended.

¹⁾ Available soon