Intelligent Technologies QCPort System Install Manual
November 2005
MN05001002E
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Page
10
QCPort Operating Modes
Overview
The QCPort system is capable of two operating modes:
•
Master-Slave
•
Peer
When the system is intended to be used in a master-slave setting there is no
configuration necessary other then setting the address (group ID) of each device to a
unique address
Peer devices require a configuration setting for normal operation. Devices that will
communicate peer are the S811 soft start and the user display (DIM).
Understanding Master-Slave
Master-Slave is when a single device (master) is responsible for scheduling all
communication to the remainder of the devices (slaves). In most cases, this will be
limited to IO applications where a Network Adapter is controlling the IO and motor control
devices. A slave only communicates when it is communicated to; thus eliminating
collisions. Since there are no unscheduled communications in a Master-Slave system,
the scan time of a QCPort system will be deterministic.
An example of a Master-Slave system can be found in Figure 3: Example of Remote
Connection Using QCPort.
Understanding Peer
Peer communication is when devices broadcast their messages on event transitions or a
time base to a specific device or groups of devices. Unlike Master-Slave, this mode has
no master scheduler in the system, and all devices produce data on an internal schedule
or when an event occurs (e.g., input transition, fault). In this mode, there is collision
detection to detect if a message is damaged by two devices talking at the same time. If
this occurs, then the devices both stand off (at different stand off times) for a period of
time and attempt to re-transmit the message.
An example of a Peer-to-Peer system can be found in Figure 2: Example of Multiple
Peripherals on One Device Using QCPort.
