YASKAWA MP900 Series User Manual

Contents

www.dadehpardazan.ir 88594014-154.2 Calculating Communications Cycle Times4-744.2 Calculating Communications Cycle Times4.2.1 Communications Cycle TimeThe communications cycle time is the time from when an I/O command is sent to aDeviceNet Slave on the network until the next I/O command transmission is made.The communications cycle time must be set when the 260IF Module is used as a DeviceNetMaster. This setting is not required when the 260IF Module is used as a Slave.Fig 4.2 Master Communications Cycle Time4.2.2 Calculating Communications Cycle TimesThe communications cycle time can be found from the total of the communications timesrequired for each Slave device.Communications cycle time [ms] =Σ (Communications time with Slave)The calculations for communications time with Slaves may differ from the actual communi-cations times depending on the length of the network and the number of connections withother devices. Communications Times with SlavesThe communications times with Slaves may be grouped in the following eight categoriesbased on the number of communications bytes of the Slave. The following abbreviations areused:No: Number of output data bytesNi: Number of input data bytesTRUND (N/7): Quotient of No or Ni divided by 7. Decimal places are truncated.MOD (N/7): Remainder when No or Ni is divided by 7.Tb: 2 for a baud rate of 500 kbps, 4 for 250 kbps, 8 for 125 kbps.1. Slaves with 8 bytes or less of output data(94+8 × No) × Tb + 600[μs]2. Slaves with 8 bytes or less of input data(94+8 × Ni) × Tb + 600[μs]Master Communications cycle timeSlaves