What are the mapping models and concurrency architectures for translating IEC 60870-5-104 telecontrol to DLMS/COSEM?

[carlos_mendez]

️ Technical Redaction & Safe Harbor Warning:
Substation telemetry maps and dispatch IP configurations have been neutralized.

In distribution automation (DTU/FTU edge gateways), SCADA master stations communicate over IEC 60870-5-104 (TCP Port 2404), while field revenue and feeder meters communicate via DLMS / COSEM (IEC 62056-53 Clause 6.2) reading voltage 1.0.32.7.0.255 and energy 1.0.1.8.0.255.
Gateways must translate 104 information object addresses (IOA) to DLMS OBIS codes for telemetry, tele-signaling, and remote tele-control.
How do engineers architect concurrent polling and event translation to prevent SCADA response timeouts during general interrogation?

[marcus_vance]

The golden rule in 104-to-DLMS gateway design per Green Book Section 7.1 is: Never synchronously poll DLMS serial meters during a 104 General Interrogation (C_IC_NA_1).

The recommended decoupled architecture:

[ SCADA 104 Master ] <=== TCP 2404 ===> [ Gateway Real-time Memory Cache ]
                                                  ▲
                                        Background Polling & Push Daemon
                                                  ▼
[ DLMS Meter Network ] <=== RS-485/TCP 4059 <=====┘

1. Telemetry (YC / M_ME_NC_1 Float):
   Gateway maintains periodic background polling loops (e.g. 1s for Voltage/Current, 15s for Energy). Master interrogation answers immediately from RAM cache.
2. Tele-signaling (YX / M_SP_NA_1 Event):
   DLMS Unsolicited Push (Class 40 0.0.25.9.0.255) alarms trigger spontaneous 104 ASDU transmissions (Cause of Transmission COT=3).
3. Tele-control (YK / C_SC_NA_1 Breaker Control):
   Translates directly to DLMS Class 70 (Disconnect Control 0.0.96.3.10.255) Method 1/2.

[alex_turner]

On the other hand, remote breaker operations (104 YK) require strict two-step execution (Select -> Execute):
When receiving 104 Execute, the gateway holds the 104 context and dispatches a High-Level Security DLMS Class 70 ACTION with a 3000ms timeout per Blue Book Chapter 4.6.
Only when the meter confirms execution with action-result: success does the gateway return 104 Command Confirmation (COT=7).

[carlos_mendez]

Per IEC 60870-5-104 Clause 7.2 and IEC 62056-53 Clause 8.2, our gateway now translates the DLMS ACTION response:

C7 01 C1 00 00

into 104 ASDU confirmation within 120ms, eliminating SCADA command timeouts while preserving metrological security.