Rockwell Automation 1760-xxxx Pico GFX-70 Controllers User Manual - Manual (Page 318)

Publication 1760-UM002B-EN-P - March 2005
6-12 Pico-Link and Point-to-Point Serial Connections
Reading and sending the network data from the CPU
The network CPU of the station reads every message on the network. If the
message is relevant to the station, it is accepted into a message memory.
If the content of a send message changes, it is sent. Transmission only occurs
when there is no message on the network.
The Pico-Link is configured so that every station can send its messages. This
means that the station must observe a pause time between sending messages.
The pause time increases the higher the number of stations and the lower baud
rate setting.
The number of stations is recognized by every station via a “sign of life” signal.
Signs of Life of the Individual Stations and Diagnostics
The inputs and outputs message type is used as a “sign of life” recognition to
ensure that the state of a station can be recognized by other stations. The states
of the inputs and outputs are sent cyclically and at the set baud rate,
irrespective of the SEND IO setting. If the inputs and outputs of a station are
not recognized by other stations after a time determined by the baud rate, the
station is deemed to be disconnected until the next “sign of life” is recognized.
IMPORTANT
The following applies to fast message transfer:
• Set the fastest possible baud rate to suit the
network length and cable cross-section.
• Fewer messages means faster messages.
• Avoid program downloads during the RUN mode.