When reading out measuring devices, temperatures and exchanging data with the PLC, the lowest common denominator is often Modbus, as it is a rather simple protocol. EES therefore supplies the universal USM fault annunciator series with Modbus TCP implementation. The fault annunciator has one or two interface cards for communication with higher-level or lower-level external systems at control or process level. The device always works as a Modbus slave (passive Modbus) with a Modbus address between 1 and 255. When using Modbus TCP, the IP address of the communication partner (Modbus master) or, in the case of Modbus RTU, the setting of the serial interface must be made in the parameterization, which is accessible via a web server on the device. The data is then available via Modbus registers or coils. Any third-party tool or device can be used to retrieve the relevant information. EES provides a defined data structure to read out various information, for example about the inputs, collective reports, horn statuses or pressed buttons and all other options, i.e. relay statuses. In addition, commands can be executed via Modbus communication to trigger relays, acknowledge messages or activate inputs in order to protect the wiring.