EtherCAT Master Settings Tab

This tab includes configurations for the EtherCAT***EtherCAT is an open, high-performance Ethernet-based fieldbus system. The development goal of EtherCAT was to apply Ethernet to automation applications which require short data update times (also called cycle times) with low communication jitter (for synchronization purposes) and low hardware costs bus master.

EtherCAT Cycle Time

Figure 4-107: EtherCAT Master Settings

Item	Description
Cycle Time	Duration of one cycle in microseconds (time = 250, 500, 1000 µs) to define the time base period for scheduling the motion and the PLC"Programmable Logic Controller" A Programmable Logic Controller, PLC, or Programmable Controller is a digital computer used for automation of industrial processes, such as control of machinery on factory assembly lines. Used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events programs (for more details on scheduling, see "Tasking Model / Scheduling")
Frame Size	It is the total size (in bytes) of the EtherCAT frame which is sent cyclically. The size is proportional to the number of EtherCAT slaves (and consequently the PDO data) on the network. The EtherCAT frame size may be between 84 to 1500 bytes.
Transmit Time	It is the time (in microseconds) that it takes to send a frame
Bandwidth Usage	It is an estimation of the percentage of the cycle time used to transmit a frame of data. BandwidthIn computer networking, bandwidth often refers to a data rate measured in bits/s, for example, network throughput. The reason for the connection of data rate with the term bandwidth is that the limit to the data rate of a physical communication link is related to its bandwidth in hertz value goes up when cycle time decreases (see calculation below)
Working Counter Error Limit	A configurable threshold for generating an E30 error and shutdown of EtherCAT communication. The default setting is 3 Errors in 1000 Frames. Other options are: Trigger on 1st Error, 2 Errors in 1000 Frames, 10 Errors in 1000 Frames, 100 Errors in 1000 Frames, or Disabled. If the Disabled option is selected the Master will keep the EtherCAT network running in op mode. It is up to the application to decide if it is appropriate to shut down the Master’s EtherCAT communication (MLMotionStop). The slave device state with regards to EtherCAT communication errors is determined by the manufacturer. AKD drives transition to Init state when 7 consecutive packet failures are encountered, and the drive executes a controlled stop. See EtherCAT Error Messages for additional working counter information.

Table 4-25: EtherCAT Cycle Settings - Form Description

The three read-only fields display (unknown) when the Use imported file option is selected (see ENI File Tab ). Otherwise, they are recalculated and refreshed each time that:

A device is added or removed
A device simulation state changes
The Use imported file check box is cleared

Bandwidth calculation algorithm

The Bandwidth (BW) usage calculation takes into account the calculated frame size and the EthernetEthernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs) speed (100 Megabits per second).

BW% = Transmission time / Cycle Time

With Transmission time (μsec) = (FrameIn networking dialect, a message is called a frame Size in bytes * 8) bits / 100 * 10⁶ bps

For example:

If Frame Size = 100 bytes
then Transmission Time = 100*8 / (100*10⁶ ) = 8 μsec

If cycle time = 1000 μsec
then BW% = 8/1000 = 0.8 %