Single Bit Data Read/Write Commands (01 / 05) – Common for HMI

Purpose and Use Cases: Certain Human-Machine Interfaces (HMIs) only support the 05 Write Command to send a signal to reset the accumulated total. Additionally, some HMIs require support for the 01 Read Command to verify that the sensor is functioning correctly.

Function Code 01 Example – Single Bit Read

This command does not reset the C02.Del.Total (Totalizer Clear) option. It is used for reading a single bit via HMI (01/05). When the 01 command is sent correctly, the slave responds by returning the requested bit status only.

Master Sends 01 (TX) Example

TX: 01 01 00 0A 00 01 A4 0E

• Slave Address: 01 (Flow meter address)

• Function Code: 01 (Read 1 bit)

• Starting Address: 02 01 (C02.Del.Total memory address)

• Quantity: 00 01 (Read 1 bit)

• CRC: A4 0E (Error check)

Slave Response 01 (RX) Example

RX: 01 01 01 00 51 88

• Slave Address: 01

• Function Code: 01 (Read)

• Data: 01 00 (Bit value, slave is online and responding)

• CRC: 51 88

Function Code 05 Example – Single Bit Write (Trigger Totalizer Clear)

This command activates the C02.Del.Total clear option, immediately resetting the totalizer to zero.

Master Sends (TX) Example

TX: 01 05 02 01 FF 00 DC 42

• Slave Address: 01

• Function Code: 05 (Write single register)

• Starting Address: 02 01 (C02.Del.Total memory address)

• Data: FF 00 (Trigger clear)

• CRC: DC 42

Slave Response (RX) Example

RX: 01 05 02 01 FF 00 DC 42

• Slave Address: 01

• Function Code: 05

• Starting Address: 02 01

• Data: FF 00 (Echoes successful write)

• CRC: DC 42