FunctionalityThe SPA protocol V2.5 is an ASCII-based protocol for serial communication. Thecommunication is based on a master-slave principle, where the IED is a slave and the PCis the master. Only one master can be applied on each fibre optic loop. A program isrequired in the master computer for interpretation of the SPA-bus codes and for translationof the data that should be sent to the IED.For the specification of the SPA protocol V2.5, refer to SPA-bus Communication ProtocolV2.5.16.4.2 Setting guidelinesThe setting parameters for the SPA communication are set via the local HMI.SPA, IEC 60870-5-103 and DNP3 uses the same rear communication port. Set theparameter Operation, under Main menu /Settings /General settings /Communication /SLM configuration /Rear optical SPA-IEC-DNP port /Protocolselection to the selected protocol.When the communication protocols have been selected, the IED is automaticallyrestarted.The most important settings in the IED for SPA communication are the slave number andbaud rate (communication speed). These settings are absolutely essential for allcommunication contact to the IED.These settings can only be done on the local HMI for rear channel communication and forfront channel communication.The slave number can be set to any value from 1 to 899, as long as the slave number isunique within the used SPA loop.The baud rate, which is the communication speed, can be set to between 300 and 38400baud. Refer to technical data to determine the rated communication speed for the selectedcommunication interfaces. The baud rate should be the same for the whole station,although different baud rates in a loop are possible. If different baud rates in the same fibreoptical loop or RS485 network are used, consider this when making the communicationsetup in the communication master, the PC.For local fibre optic communication, 19200 or 38400 baud is the normal setting. Iftelephone communication is used, the communication speed depends on the quality of theconnection and on the type of modem used. But remember that the IED does not adapt itsspeed to the actual communication conditions, because the speed is set on the local HMI.1MRK 505 337-UUS - Section 16Station communication445Application manual
