Infrastructure mode

SCALANCE W-740 Client Modules make it possible for a station with an Industrial Ethernet interface (e.g. a controller) to move seamlessly and with no wear in an Industrial Wireless LAN radio link (e.g. with SCALANCE W-780 Access Points). The station registers in the radio link via the Ethernet Client Module and can exchange information with the entire data network. If the Ethernet Client Module e.g. moves on an automated guided transport system, it is automatically and transparently transferred from one Access Point to the next (roaming).

This is possible over distances of up to 30 m indoors (approx. 100 m outdoors). Directional additional antennas can be used outdoors to achieve ranges of several thousand meters.

Apart from a reliable radio link, the SCALANCE W-740 Client Modules are characterized by excellent support from IT mechanisms:

• IEEE 802.11 b/g/a/h for different frequency ranges
• IEEE802.11e fur multimedia, wireless multimedia (WMM)
• IEEE802.11i for security
• Selectable operation of infrastructure- and Ad-Hoc modes
• Sending the log entries of the SCALANCE W devices to a Syslog server
• Network and Port Address Translation (NAT/PAT) (mapping of private IP addresses and ports onto public addresses)
• Modern security mechanisms (e.g. network security such as IEEE 802.1x, RADIUS, EAP mechanisms)

Ad-hoc mode

In this infrequently used mode, a simple radio link is established between several mobile devices without using an Access Point. In this case, an Ethernet Client Module can communicate with another SCALANCE W-740 device or with a standard WLAN radio card.

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 code as well as performing the access check (authentication) of a station. The Advanced Encryption Standard (AES) is available for data encryption. All encryption mechanisms are integrated in the products and do not incur any additional costs.

Access to the devices (HTTPS) is encrypted and secure logon (SSH) is possible. If a security concept with Virtual Private Networks (VPN) or the SCALANCE S range is required, the products can be integrated without any difficulty.

Mobile controls in an automatic guided vehicle (AGV)

The controllers register via the Ethernet Client Modules W746-1PRO in the radio link and can move around freely there. This makes it possible to operate an automated guided vehicle system (AGVS), for example.

Use of the Ethernet Client Modules in a suspended monorail

The mobile units of a suspended monorail, for example, are linked to the IWLAN radio link via the Ethernet Client Modules SCALANCE W747-1. This is implemented by means of the SCALANCE W788-2RR Access Points and the RCoax cable. The Ethernet Client Modules are mounted in cabinets because of their mechanical characteristics.

Functional scope

SCALANCE W744-1PRO and SCALANCE W744-1 can administer one single IP address, namely that of the connected device. They establish a wireless connection precisely from this mobile device to the radio network. If the connected device is replaced, the Ethernet Client Module recognizes this automatically, and registers the new address. This reduces plant downtimes and sources of error.

The SCALANCE W746-1PRO and SCALANCE W746-1 Ethernet Client Modules can administer the radio connection for up to eight devices with an Ethernet interface. It is then possible to very effectively integrate mobile units with a small Ethernet network (up to eight devices) into an IWLAN radio link.

All Ethernet Client Modules (except W744-1 and W744-1PRO) feature DHCP server functionality. Thus you can assign dynamic IP addresses to up to eight connected stations which are in the subnet behind the Client Module.

Assignment of dynamic IP addresses to wirelessly connected stations by a central DHCP server or integrated DHCP server of an IWLAN client module

iFeatures (only for RR versions of the Client Modules)

iPCF (industrial Point Coordination Function)

The iPCF mode is recommended for applications with a requirement for real-time and predictable response times (deterministic response), even during roaming of moving stations 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 integrated into the radio link. This means that even video signals from moving stations 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 station and the Access Point (e.g. SCALANCE W788-1RR). In a radio link in which iPCF is used, no IEEE 802.11-compliant stations can be operated.

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

Note:
The IWLAN/PB Link PN IO network transition also supports iPCF

iPCF-MC (iPCF Management Channel)

iPCF-MC is available as further development of iPCF. This mode should be used if IWLAN stations that also support iPCF-MC (e.g. Client Modules SCALANCE W747-1RR, Mobile Panel 277F IWLAN) move freely about in the coverage area (especially when using omni-directional antennas) and are to exchange data deterministically. This functionality can only be implemented in combination with RR Access Point versions with at least two radio interfaces.

Note: Due to the lower bandwidth when using iPCF-MC, we recommend the iPCF mode for transmitting video signals.

Roaming of a mobile panel between two access points while maintaining error-free communication with iPCF-MC

iHOP

With the supplementary function iHOP, the Access Point changes the channel in coordination with its clients. If it detects interferences which are caused, for example, by sporadically active WLANs on a channel, it avoids the affected channel temporarily. Hopping to the other channel is carried out so rapidly that usually the application is not impaired by the channel change. If the interferences occur throughout the complete frequency band, it is even possible to change to another frequency band (e.g. from 2.4 to 5 GHz). This guarantees reliable communication even with interferences in the radio field.

Coordinated changing of channels by means of a channel hopping procedure (iHOP) to avoid disrupters

Dual Client

This function permits coupling of two Client Modules via an Industrial Ethernet Switch (e.g. SCALANCE X-200). One client is actively connected to an Access Point via IWLAN. The other client is in standby mode and continuously searches for an Access Point with better signal strength. If it finds one, its status changes to active and the previously active client switches to standby mode. Changeover between the clients is implemented without interrupting communication (seamless roaming).

Two linked IWLAN client modules form a dual client to enable uninterrupted roaming for fast moving vehicles

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
• Planning, configuration, simulation and measurement of the radio link on site (Site Survey) with SINEMA E
• LEDs for signaling operating states and fault conditions
• Signaling of faults by means of SNMP trap or e-mail to a network management tool
• Optional swap medium C-PLUG (Configuration Plug) for easy replacement of the module without a programming device in the event of a fault