EtherCAT · Production line
One frame, every machine: how EtherCAT moves data on a production line
The controller builds one frame every cycle, with a place for every device on the line. As it passes, each device takes its command out and writes its answer back in, in hardware, in transit. Measured on our bench: 19.2 µs average, 30.9 µs maximum, 0% packet loss.
Chapters
ILLUSTRATION + BENCH DATA
The cabinet, the arm, the humanoid and the car are 3D illustrations, and the CAN comparison is structural, not a measurement. The latency figures in the film were measured on our own bench; the setup is listed below.
01What the film shows
A production line is a few hundred devices that have to agree on when. EtherCAT's answer is one frame per cycle: it leaves the controller, passes every device and comes back. No packet per device, no store-and-forward at every node.
The film follows one frame through a plant: the servo drives, the six axes of the arm welding a car body, the joints of a humanoid on the same line, and finally the car that line built. The car runs a different bus: CAN sends eight bytes per message, one message at a time.
The cabinet, the arm, the humanoid and the car are our own 3D illustrations, and the CAN comparison is structural. The bench numbers are ours. The master stack is Class B and does not use distributed clocks, so we quote no DC figures. We do not sell an EtherCAT master: we bring lines up on TI silicon and characterise their timing.
02Bench data
1 slave, 64-byte process data, 10 kHz cycle. Master: TI Sitara AM572x (PRU-ICSS), TI-RTOS, a commercial Class B master stack; slave: TI Delfino TMS320F28388D; 100 Mb/s link. The stack does not use distributed clocks, so no DC figure is quoted. Full tables and method
03Transcript
A machine is a set of parts that must agree on when.
EtherCAT answers with one frame, built fresh every cycle, with one slot for every device on the line.
It never stops. Each device takes its command out, and writes its answer back in.
This is what moves a welding arm. Six joints, one frame, one pass.
The same line runs a humanoid. Thirty joints. Ankle, knee, waist, elbow, hand, neck. The gyro in the head. The focus and zoom motors in the eye.
The car that line just built runs a different bus. CAN sends eight bytes per message, one at a time, and everything else waits its turn.
One mechanism, from the machine that builds the car to the car itself.
On our bench: nineteen point two microseconds average, thirty point nine maximum, zero packet loss.
Spikedge. We measure the cycle.
