For annunciating systems the challenge today is to fit in the numerous requirements which are present in substation integration. On the one hand galvanic isolated contacts are necessary to process conditions of dry contacts in different voltage levels. On the other hand protocols are welcome to forward information on the station buses without the effort of wiring like on IEC 61850.
In regard of reading out metering devices, temperatures, data exchange with PLC the smallest common factor is often Modbus, as it is a rather simple protocol. Since October EES is delivering its universal fault annunciator series “USM” with the free of charge Modbus TCP implementation.
For communication with superior or inferior third party systems in the control or process level, the annunciator provides one or two interface cards, while the latter is on surcharge providing also Modbus RTU, if needed.
The device operates always as a Modbus slave (passive Modbus) with a Modbus address between 1 and 255. If Modbus TCP is used, the IP address of the communication partner (Modbus master) or for Modbus RTU the settings for the serial interface must be set in the parameterization which is accessible on the device through a webserver. Then data is accessible via Modbus-registers or -coils.
To retrieve the respective information any 3rd party tool or device can be taken. EES offers a defined data structure as reports were e.g. various information about the inputs, collective reports, horn conditions or buttons pushed and all other options i.e. relay states can be read out.
Else also commands can be carried out using Modbus communication to trigger relays, acknowledgement commands or even to activate inputs in case of sparing the wiring.
To round off the flexibility with the USM from EES the protocols can be mixed together and by this form a gateway for maximum flexibility needs. Individual inputs can be set by Modbus TCP while forwarding the whole process image on IEC 61850.
Be flexible – coping with todays and tomorrows needs in one consolidated device. USM – the universal fault annunciator.