Rockwell Automation 1756-SYNCH ControlLogix SynchLink Module User Manual - Manual (Page 37)

Publication 1756-UM521C-EN-P - July 2004
SynchLink Module Features 3-9
The SynchLink module updates its receive and transmit buffers once
every 500μS. Because direct data can be passed through from node to
node once every 50μS, up to 10 nodes can be updated with direct
data in a single 500μS SynchLink scan. Pass-through functionality only
applies to direct data in a daisy chain configuration, though; axis data
and buffered data cannot be passed through. Instead, these data types
require the intervention of the local controller to move data along. For
this reason, it is not recommended that a daisy chain configuration
be used when distributing axis data among multiple axis in a
distributed control system.
For more information on the available Receive Port and Transmit Port
communication formats, see Table 3.4.
Table 3.4 SynchLink Module Receive Communications Formats
Receive Port Communications Format Transfer Rate (across the fiber optic
cable) for Each Data Type:
1 Axis, 3 Direct Words, 14 Buffered Axis Data - Updated every 500
μS
Direct Data - Updated every 50
μS
Buffered Data - Updated every 500
μS
2 Axis Axis Data - Updated every 250
μS
2 Axis, 3 Direct Words Axis Data - Updated every 500
μS
Direct Data - Updated every 50
μS
2 Direct Words, 18 Buffered Direct Data - Updated every 50
μS
Buffered Data - Updated every 250
μS
4 Direct Words, 18 Buffered Direct Data - Updated every 50
μS
Buffered Data - Updated every 500
μS
4 Direct Words, 8 Buffered Direct Data - Updated every 50
μS
Buffered Data - Updated every 250
μS
No Receive Data No data updated in this format