5.3 MEMOBUS/Modbus Communications234 YASKAWA ELECTRIC SIEP C710617 01B YASKAWA AC Drive GA700 Technical ManualNote:Set DIP switch S2 to the ON position to enable the termination resistor in the last drive of the MEMOBUS/Modbus communicationnetwork.◆ Drive Operations by MEMOBUS/ModbusThe parameters of the drive apply to the settings even if the drive is run during MEMOBUS/Modbuscommunications. This section describes the types of usable functions and their related parameters.■ Executable FunctionIf the PLC is used, the following operations can be executed during MEMOBUS/Modbus communicationsregardless of the setting of the parameters (excludingH5-xx).• Run the drive from the PLC and monitor its operation status• Parameter Settings/References• Fault Reset• Multi-function input setting (The input command for MEMOBUS/Modbus communications is the commandinput from MFDI terminal (S1 to S8) and OR.)■ Drive ControlSelect the external command for setting the frequency references and the motor run/stop using MEMOBUS/Modbus communications, and set the parameters according to the application using the following table.Table 5.2 Required Parameter Setting for Drive Control from MEMOBUS/ModbusOperation Mode No. Name SettingExternal reference 1b1-01 Frequency Reference Selection 1 2 [Memobus/ModbusCommunications]b1-02 Run Command Selection 1 2 [Memobus/ModbusCommunications]External reference 2b1-15 Frequency Reference Selection 2 2 [Memobus/ModbusCommunications]b1-16 Run Command Selection 2 2 [Memobus/ModbusCommunications]For more information on operation mode selection, refer to b1-01 [Frequency Reference Selection 1] and b1-02[Run Command Selection 1]. For more information on external command, refer to H1-xx = 2 [MFDI = ExternalReference 1/2 Selection].◆ Communications TimingTo prevent overrun of the slave side, the master cannot send a message to the same drive for a certain amount oftime. Similarly, to prevent overrun of the master side, the slave cannot send a response message to the master for acertain amount of time. This section explains the message send/receive timing.
