We are encountering an RCB (Report Control Block) communication issue while integrating Zenon 14 SCADA with a Hitachi Energy RED670 IED over the IEC 61850 MMS protocol.

A verification of the RCB configuration and assignments on both the Zenon SCADA system and the RED670 IED indicates that the report subscriptions are configured correctly.

However, analysis of the communication trace captured using Wireshark reveals that, after issuing GetDataDirectory requests, Zenon proceeds to send GetDataValue (read) requests directly for the data objects, rather than performing the expected sequence of RCB discovery, configuration, and report enablement (e.g., setting the Report Control Block parameters and enabling reporting).

Interestingly, this behavior is not observed when integrating the same Zenon system with Siemens 7SL series IEDs, where report control blocks are successfully enabled and report-based communication operates as expected.

Why Zenon is resorting to cyclic MMS polling (GetDataValue requests) instead of attempting to reserve and enable the available RCBs on the Hitachi RED670 device? Specifically, are there any known interoperability constraints, IEC 61850 implementation differences, or configuration requirements that would cause Zenon to fall back to polling mode rather than utilizing report-based data acquisition?