The SMG (Slotted Microwave Guide) data transmission system is suitable in automation technology for contactless and interference-free transmission at high data rates up to 10 Mbit/s for all track-guided vehicles and opens up a wide range of applications through its variable design.
SMG was originally developed by MBB (Messerschmitt-Boelkow-Blohm), now DASA (Deutsche Aerospace), to transmit data to the magnetic levitation train (»Transrapid«) traveling at speeds of up to 250 mph. VAHLE acquired this product by the end of 1994 and now has over 1000 installations successfully in operation worldwide.
VAHLE has embarked on an extensive development program to increase the SMG application range. Presently there are already data interfaces available for the most commonly used bus systems. Heavy-duty construction makes it possible to install SMG in arduous and environmentally difficult locations; for instance a great number of SMG waveguide systems are functioning reliably in steel mills, foundries and harbors.
The SMG data transmission system operates economically already with single channel transmission and low data rates. Modular design easily expands the system to handle at relativley low cost medium and high data rates as well as multi-channel configurations. When combined with VAHLE conductor systems for the current supply, SMG data transmission systems become a reliable high-performance component package capable of handling a wide variety of applications as demanded by current and future automation technology.
The SMG system is designed for the transmission of digital, serial data, as generally typical in data communications networks, as well as also for the transmission of video signals. Special transceivers (transmit/receive devices) with interface modules for all common bus systems prepare the digital, serial signals for transmission by means of frequency modulation.
For full-duplex transmission of the usable signals, two carrier frequencies in a range around 2.4 GHz are available. A specially shaped aluminum extruded profile (slotted hollow conductor) between the transceivers is used as the transmission medium.
Through the transparent layout, as well as the support of numerous data protocols, the SMG system can be integrated into existing bus systems without a problem. If needed, for this purpose VAHLE also provides suitable engineering services.
SMG Special Features
- Immunity to interference due to isolation of the SMG profile from the surroundings.
- Maintenance-free due to contactless transmission technology.
- Common assembly of the SMG profile with all VAHLE current conductors, Powerail conductors and the CPS system.
- Error-free transmission of high data rates up to 10 Mbit/s.
- Simultaneous transmission of up to six data channels full duplex.
- Transmission paths of up to 1000 m without intermediate amplification due to high dynamic response of transceivers.
- Simple adaptation to the customer&s computer peripherals, as well as good expansion possibilities due to modular device construction.
- EMERGENCY-OFF transmission according to stop category 1, safety level 3.
- Coupling of several mobile subscribers to one SMG profile.
- Transmission independent of traveling speed of mobile subscriber.
- No negative effects on transmission quality due to environmental influences, e.g., temperature, humidity, clouds, dust, etc.
- Also suiable for tracks with curves, breaks and switchpoints.
The SMG data transmission system provides many interfaces for the most common bus systems (RS 232 C, RS 422/485, Ethernet, Allen-Bradley Data Highway Plus, Allen-Bradley remote I/O, GE Genius, and many more) as well as special interfaces for video, audio, control signal and emergency shutdown transmission. All interfaces are formed as plug-in modules and thus can be easily adapted to the existing communications structure.
The SMG-SES/SEM transceiver unit is equipped with the RF module and the 24 VAC/DC power supply module. It is designed to accept the SMG-DM data module.
Data module SMG-DM
The SMG-DM data module is prepared to accept the SMG-DM.. interface module and is equipped with a connector for the customer&s existing communication system.
Interface module SMG-SM
The SMG-SM interface module is used to adapt to the serial data signals of the customer&s existing communication system.
Mounting of the SMG waveguide
The SMG waveguide is installed parallel to the vehicle track, slot opening pointing downward. The waveguide is supported with sliding hanger bracket on 3 m centers and may be installed together with the conductor system.
Standard length for a SMG waveguide section is 6 m. Sections are joined with bolted joint splice clamps to make the required system length. Be certain to have at least 200 mm clearence between joint splice clamp and hanger bracket.
The support hanger permits the waveguide to slide freely during thermal expansion or contraction. Systems up to 200 m long may be anchored anywhere along the system with the included anchor bracket so that controlled expansion/contraction is assured.
For installations exceeding 200 m and having large temperature variations, the SMG waveguide must be anchored at the center of the system.
Be certain that the last sliding hanger bracket is positioned with sufficient spacing to the track end and there is adequate clearance between the waveguide connector SMG-PV and carrier SMG-HT.9e -2 - SMG - Slotted Microwave Guide