C.6 Communications TimingTo prevent a communications overrun in the slave drive, the master should wait a certain time between sending messages tothe same drive. In the same way, the slave drive must wait before sending response messages to prevent an overrun in themaster. This section explains the message timing.u Command Messages from Master to DriveThe master must wait for a specified time between receiving a response and resending the same type of command to the sameslave drive to prevent overrun and data loss. The minimum wait time depends on the command as shown in Table C.3.Table C.3 Minimum Wait Time for Sending MessagesCommand Type Example MinimumWait Time1• Control command (Run, Stop)• Set inputs/outputs• Read monitors and parameter values5 ms <1>2 Write parameters H5-06 = 0: 50 msH5-06 = 1: 200 ms <1>3 Save changes using an Enter command200 ms to 2 s, depending on thenumber of parameters thatwere changed <1>4 Enter with storage to drive EEPROM after initialization 5 s<1> If the drive receives command type 1 data during the minimum wait time, it will perform the command and then respond. However, if it receivesa command type 2 or 3 during that time, either a communication error will result or the command will be ignored.Set a timer in the master to check how long it takes for the slave drive(s) to respond to the master. If no response is receivedwithin a certain amount of time, the master should try resending the message.u Response Messages from Drive to MasterIf the drive receives a command from the master, it will process the data received and wait for the time set in H5-06 until itresponds. Increase H5-06 if the drive response causes overrun in the master.TimeCommand message Response message Command messagePLC→Drive PLC→DriveDrive→PLC24 bit length H5-06settingFigure C.6 Minimum Response Wait TimeC.6 Communications TimingYASKAWA SIEP YAIP1U 01C AC Drive - P1000 Technical Manual 515C MEMOBUS/ModbusCommunications
