User Documentation

Communications

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9. Communications

9.1 Communication procedures

Communication starts with command transmission from the host computer (hereafter referred to as Master)

and ends with the response of Power Monitor (hereafter referred to as Slave).

• Response with data

When the Master sends reading command, the Slave responds with the

corresponding set value or current status.

• Acknowledgement

When the Master sends setting command, the Slave responds by send-

ing the acknowledgement.

• Negative acknowledgement

When the Master sends a non-existent command or value out of the

setting range, the Slave returns a negative acknowledgement.

• No response

The Slave will not respond to the Master in the following cases:

• Global address “FF” (MEWTOCOL) is set

• Broadcast address “00H” (Modbus protocol) is set

• Communication error (framing error, parity error)

• CRC-16 discrepancy (Modbus RTU mode)

• CS discrepancy (DL/T645)

Master

Slave

Acknowledgement

Command

Negative

acknowledgement

Command

No response

Command

Data