The EDT features an additional RS-485 slave port that exactly duplicates the functionality of the Modbus port on the EIM. This port is always active. The port will respond to the same Modbus IDs and register requests as the EIM. The EIM must be present for this port to operate.
The additional RS-485 slave port is useful in situations where two SCADA systems want to collect data from the system. One system can be connected to the EIM Modbus port, and the other can be connected to the EDT RS-485 slave port. This functionality is available whether the EDT is used with an ECU or not, so this can be used as a stand-alone feature.
The RS-485 slave port can be set up by selecting “Slave MB Port Settings…” button on the main EDT Setup page.
The top part of this page is used to select the baud rate and line control mode for the port to match the SCADA device used.
If in “Engineering” access mode, the setting on the bottom part of the screen becomes active. This setting selects whether the RS-485 slave port should restrict write commands. If set to ‘Yes’, then any register write commands are rejected on that port. The EIM Modbus port will still always allow writes. This feature can be used if there are two SCADA systems but only one should have write access.