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IEC-101 command flow

A command is not only one frame. It is a short protocol exchange that should create confirmation, possible feedback, and completion evidence.

What it means

A command is not only one frame. It is a short protocol exchange that should create confirmation, possible feedback, and completion evidence.

SelectOptional in select-before-operate workflows. The device reserves or prepares the command.

ExecuteThe actual operate request. Address, COT, qualifier, and IOA must be correct.

ACTCONActivation confirmation. The slave accepted or rejected the activation.

Feedback / ACTTERMThe process value and termination evidence tell whether the command completed as expected.

What to check in ARIEC60870

Use the software to connect the explanation to the frame evidence.

1If ACTCON is missing, check link state, CA, IOA, command type, and flow control.

2If ACTCON exists but feedback does not change, the protocol path may be good while the field process is not.

3ARIEC60870 report evidence is useful because it keeps the command story together.

TX10 49 01 4A 16request link status

RX10 0B 01 0C 16ACD=1, Class 1 waiting

TX10 7A 01 7B 16request Class 1 data

RX68 ... 16event or command confirmation

Protocol learning is easier when every concept is connected to a visible frame, counter, address, value, event, or report finding.