Rockwell Automation 1336T FORCE Series B - Manual (Page 108)

Chapter 4
Startup
4–17
Communication Configuration
Drive to Drive Communication – Drive to Drive Communication (D2D)
provides high speed communications between drives. D2D is capable of
connecting up to 64 Drives together using three different transfer rates,
125K (64 nodes), 250K (64 nodes), and 500K (32 nodes) baud.
Hardware Setup – Refer to Chapter 2 Installation for Drive to Drive
wiring, L Option wiring and Pulse Input Configuration.
Data Transfer – The D2D which allows multiple transmitters to
broadcast information based on priority to multiple receivers which choose
the information they wish to receive. The D2D will operate at three
different baud rates as shown in the following chart.
Baud Rate
125k
Max. Distance (End to End)
250k
500k
Data Rate
330m
140m
50m
600us
300us
150us
Max. Transmitters (2ms task)
3
6
13
The baud rate choices allow for different end to end distances and number
of transmitters. The distance is based on the propagation delay of the
signal through the wire and the maximum transmitters come from not
exceeding the 2ms task. The propagation delay is based on CAN variables.
The number of transmitters is based on the data rate.
2 ms
600us (1) 600us(3)
600us(1) 600us(4)
600us (2)
2 ms
600us (1) 600us(3) 600us (2) 600us (1) 600us(3) 600us (2)
600us(2) 600us(3) 600us(1) 600us(2) 600us(3)
2 ms
Shown above is the D2D set at 125k baud with 3 and 4 transmitters. With
3 transmitters, the data rate never exceeds 2ms and all the data is received
within the 2ms task. In the case of 4 transmitters, the fourth transmitter
does not always get transmitted due to the priority of the transmitters. The
lower the node address the higher the priority. All the data is not seen
every 2ms task. Data transfer errors also effect how much data is
transferred. Errors in the transfer will cause retransmission of the data and
may cause the data rate to exceed 2ms. Within the drive itself, the Velocity
Processor (VP) will be running the D2D in its 2ms task. With the use of
D2D indirects, data can be transferred within 2–3ms from one drive to
another and 4–5ms from one drive to another and back.
Velocity
Functions
D2D Xfer
150us
300us
600us
Data Transmitted
D2D
Rx
150us
300us
600us Velocity
Functions
2 ms Task
D2D
Tx
D2D
Tx
D2D Xfer
D2D
Tx
2 ms Task
D2D
Tx
The D2D receive and transmit are on both sides of the velocity functions.
This is to improve the data rate.