8502-BI-DP supports 24 I/O modules

Description

The 8502-BI-DP Bus Interface Module (BIM) provides the communications link between the 8000 series I/O modules and a Profibus-DP host. Its high speed acquisition of data from the modules and LAN operation speeds of up to 6 Mbaud allows the host to respond rapidly to conditions in the control process.

The BIM gathers the data from the I/O modules and makes it available to the host upon request. It is a slave to the Profibus master. As well as cyclic data exchange, which is required for reading input and writing output data, the BIM supports Profibus Extended Diagnostics for status information. It also supports a number of special features which have been implemented to allow high integrity system operation and in-situ maintenance.

The 8502 supports parameterisation from the Profibus master. This configures on a “per module” basis, i.e. all the channels on a single module carry the same configuration. The configuration is created in a Profibus configurator using details provided in a GSD file. This method is fast and enables a configuration to be built based upon “logical” modules which represent the physical modules.

Modules are added one at a time to the configuration and parameters are chosen to apply to all the channels of the module. Logical modules can be selected to provide HART status and process variables in the Profibus-DP cyclic input telegram. In addition, for applications where access to many HART variables is required, the HART “mailbox” can be used.

This technique collects HART variable as they are required; saving space in telegrams that are sometimes overworked with data. This method is available only when using parameterisation. The configuration is passed down from the Profibus master to the BIM at the start of the session. If the system is stopped and re-started, the configuration file is re-transmitted to the BIM.

DCS is the abbreviation of Distributed Control System, commonly referred to as Distributed Control System in China. Its significance lies in “decentralized control and centralized management”. It is a multi-level computer system composed of process control level and process monitoring level, connected by a communication network. It integrates 4C technologies such as computer, communication, display, and control. The basic design concept of DCS control system is decentralized control, centralized operation, hierarchical management, flexible configuration, and convenient configuration.

The current problems in our company’s DCS control system
1. The fault has not been truly dispersed. At present, the DCS control systems put into operation in various power plants of our company are basically the same in structure, consisting of controllers, power supplies, I/O modules, communication modules, racks, communication networks, and human-machine interfaces. The only difference is that the redundancy of controllers, power supplies, communication networks, and engineer stations varies, and the number of I/O modules or channels varies, resulting in different numbers of modules carried by the racks. In the past few years of operation, there have been cases where certain faults (such as communication interruption) have caused the entire DCS system to crash and forced the host to shut down. The control tasks undertaken by the controllers of the DCS system cannot be geographically dispersed like traditional instrument control systems, thus making it impossible to truly disperse faults.

2. The goal of saving cables has not been achieved. Due to the delicate equipment components of the DCS system and high environmental requirements, the main equipment of the DCS system is generally located in the electronic room with good conditions, and a large number of on-site signals still need to be connected to the electronic room through cables. Therefore, compared to traditional instrument control systems, there is not much cable savings.

3. Difficulty in purchasing spare parts. Due to the high cost of the modules in the DCS control system, it is not possible to purchase a large number of spare parts. However, due to the rapid upgrading of electronic products, it is often difficult to purchase suitable spare parts in a few years.

4. The dependence of unit operation on DCS system manufacturers has increased. Especially for some foreign DCS products, the application of DCS systems is not satisfactory due to the widespread shortage of technical talents and low quality of operating personnel. The dependence on DCS system manufacturers has not decreased but has increased, especially during the new construction and commissioning period of the unit. The expert services sent by DCS manufacturers to the construction site seem to be essential during the commissioning period of the unit. At the same time, in order to make good use of the DCS system, the engineering and technical personnel required for training and the cost of training have also increased.

5. The control function of the DCS system is not perfect enough. Due to the fact that most of our company’s boilers are circulating fluidized bed boilers that burn coal slurry and gangue, almost every power plant’s DCS control system has not achieved automatic control and regulation of combustion. Due to selection reasons, some power plants’ DCS systems cannot even achieve functions such as SOE and ETS.

6. The manufacturers of the DCS control systems operated by each power plant of the company are different, making it difficult for thermal technicians to communicate, and the spare parts for the DCS systems of each power plant are not interchangeable, which increases the company’s operating costs.