ABB UAC389AE02 HIEE300888R0002 Low voltage AC frequency converter

The second level network of ABB UAC389AE02 HIEE300888R0002 is the communication between controllers, connecting three types of controllers that complete different tasks on one bus, known as the control bus. There is no limit to the number of different controllers on the control bus. In addition to three different controller modules, there are also interface modules for the DCS network on this bus. On the control bus, data can be called between controllers. Make the combination between analog and switch quantities very good. The control bus is not available in every DCS system, and various controllers can be connected to the DCS network separately. The data calls between controllers need to be made through the DCS network. The speed situation of the control bus is similar to that of the VO bus. Usually between tens of K and a few megabytes. When the CPU and memory have strong capabilities, both the logic operation of switch signals and the acquisition function of analog signals are completed in one controller. There are only one form of controller on the control bus. Its protocol adopts carrier monitoring, broadcast transmission, and a protocol similar to Ethernet

ABB UAC389AE02 HIEE300888R0002 connects the on-site controller and human-machine interface into a system. In order to ensure successful communication, DCS manufacturers make both cables and communication ports several times. When one network fails, the other backup network is immediately put into operation. The backup methods vary among various DCS. The MAX-1 system of LEEDSNORTHROP in the United States uses redundant dual loop information to operate both forward and backward simultaneously. Some systems have one loop running and another waiting vehicle on the DCS communication network, which is called a node. In terms of geographical location, nodes can be dispersed and configured, and the distance between each node varies depending on the DCS system. Some can reach several hundred meters. The transmission rate ranges from a few hundred K to one hundred megabytes. 10 Mbps is a commonly used rate. The total length of the DCS network can reach several kilometers, with the shortest being several hundred meters. When the network is not long enough, a repeater needs to be added.