24 V Power Supplies and ASi – a cost-effective combination for very small systems
Using ASi with 24 V Power Supplies
Do you intend on realizing ASi networks in a cost-optimized way through 24 V power supplies? Not a problem – only three requirements have to be met: it must be a very small system with only a few ASi nodes, the ASi cable length must be less than 50 m and suitable gateways with integrated decoupling coils need to be used. Bihl+Wiedemann offers a broad range of devices so that you can always choose between different gateway options to suit your requirements.
Please note that 24 V power supplies are not optimized for ASi-5 communication. Our 30 V power supplies are the ideal solution for this purpose. They have been specially developed for parallel ASi-5/ASi-3 communication.
Advantages of ASi with 24 V power supplies
If you realize ASi networks with 24 V power supplies, you will benefit from three advantages in particular:
- Save space in the control cabinet, as the existing standard power supply can be used for powering the ASi circuit.
- Less documentation and installation time, as the matching gateway only needs to be connected to the 24 V power supply.
- Save costs, as no additional ASi power supply is required and no back-up fuse is needed.
Gateways with decoupling coils required
To use ASi in combination with 24 V power supplies, you need ASi gateways with integrated decoupling coils. This applies to all ASi-5/ASi-3 gateways and to most ASi-3 gateways. Suitable ASi-3 gateways from Bihl+Wiedemann can be recognized by the fact that the criterion "Integrated decoupling, ASi current measurement in the gateway" is met in the technical data. Here you can find the corresponding gateways
Which gateway option is the right one?
ASi-5/ASi-3 gateways are the best choice. They incorporate the state-of-the-art technology of ASi-5 and are at the same time the most powerful ASi-3 masters on the market. ASi-5/ASi-3 gateways also offer further advantages:
- Integration of ASi-5 nodes, e.g., for IO-Link devices or for drives solutions
- Field update capability for tamper-proof updates of firmware and security features
- Integrated OPC UA server for Industry 4.0 / IoT applications
- Integrated web server for fast system diagnostics
When a faulty gateway needs to be replaced, pure ASi-3 gateways can still be used: We always recommend to use a replacement device with the same item number. It is also important to know that there are also fieldbuses (e.g. PROFIBUS) that are still used in existing systems but do not provide the necessary bandwidth to support ASi-5. Even in this case, the use of a cost-effective ASi-3 gateway is still recommended.
Maximum ASi cable length of 50 meters
Generally, the resistance of a cable grows with its lengh. Therefore, when using 24 V power supplies, you should never exceed theASi cable length of 50 meters as otherwise the voltage drop across the cable could be too high, thus resulting in insufficient voltage at the end of the line.
This formula applies: U = R × I (voltage = resistance × current)
Fig.: For ASi gateways with integrated decoupling coils, you are always flexible on the power supply side: either by using our modern power supplies or – if the cable length is small enough – with 24 V from the control cabinet.