DLMS Disconnect Control (Class 70) Remote Cut-off and Reconnection State Machine

[david_miller]

Engineering Guide: Disconnect Control (Class 70)

Managing internal contactors for demand limiting or prepayment requires strict adherence to the Class 70 state machine defined in IEC 62056-62.

Object Identification

• OBIS Code: 0.0.96.3.10.255 (Disconnect Control 1)
• Class ID: 70

Control Methods

• Method 1 (remote_disconnect): Opens the contactor (Disconnects supply).
• Method 2 (remote_reconnect): Closes the contactor or enters 'Ready for Reconnection' state.

Output State Validation (Attribute 2)

Control State Value	Meaning	Physical Contactor Status
0	Disconnected	Open (No power)
1	Connected	Closed (Power active)
2	Ready_For_Reconnection	Open (Awaiting manual button press on meter)

[!IMPORTANT]
Safety regulations in many jurisdictions forbid immediate remote closure if someone is working on site. Setting control_mode = 2 transitions the meter to state 2, requiring the consumer to press the meter physical push-button to complete the circuit.

[carlos_mendez]

From field experience: Always read Attribute 3 (control_state) immediately after executing remote_reconnect. If the meter is configured in Safety Mode, the state will read 2 (Ready_For_Reconnection) rather than 1 (Connected). The consumer display will show a blinking reconnect icon.

[elena_rostova]

In the meter firmware, contactor pulse duration is controlled via Attribute 4 (output_signal). We configure a 200ms pulse for the magnetic latching relay to prevent coil overheating.