AS-P892-000 Output module

A parameter is an operating instruction for the drive. Parameters can be read and programmed with the drive control panel, or through the NMBA-01 Module. Communication Module Communication Module is a parameter name/parameter selection name for a device (e.g. a fieldbus adapter) through which the drive is connected to an external serial communication network (e.g. a fieldbus). The communication with the communication module is activated with a drive parameter. NMBA-01 Modbus Adapter Module The NMBA-01 Adapter Module is one of the optional fieldbus adapter modules available for ABB drives. The NMBA-01 is a device through which an ABB drive is connected to a Modbus serial communication bus.

Data Sets and Data Words

 Data sets are clusters of data sent through the DDCS link between the NMBA-01 Adapter Module and the drive. Each data set consists of three 16-bit words, i.e. data words. The Control Word (sometimes called the Command Word) and the Status Word, References and Actual Values (see Chapter 6) are types of data words; the contents of some data words are user-definable. Broadcast Write Modbus network allows the Modbus master to perform a write to every slave station at the same time. This write is called Broadcast. This service does not give verification back to the master that the value has been received by each one of the slaves properly.Modicon PLCs have a signed integer data table area, which is used for Analogue Output modules and for storing temporary or set-point values. These registers are in the address area starting from 40001. The last register address available on PLCs depends on the available memory, but is less than 49999. The drive simulates this area by providing a read and write access to its parameters through this register address area.

This chapter describes the NMBA-01 Modbus Adapter module, and gives the Warranty and Liability information of the Manufacturer. (Information about the Modbus protocol is available in Appendix B.) Introduction to Modbus Modbus is a serial, asynchronous protocol. The Modbus protocol does not specify the physical interface. The typical physical interfaces are RS-232 and RS-485. The NMBA-01 uses the RS-485 interface. Modbus is designed for integration with Modicon PLCs or other automation devices, and the services closely correspond to the PLC architecture. The NMBA-01 ‘looks like’ a Modicon PLC on the network.