Instructions ECL Comfort 210 / 310, communication description
9.4.4 Parallel network
If a large number of controllers is used in a limited area with a limited length of the communication cable, parallel network might
be a way to generate more bandwidth.
If the master is located in the middle of the network, the network can easily be split-up into two and the bandwidth can be
doubled.
9.4.5 Bandwidth considerations
Modbus is based on a command/query and response, meaning that the SCADA system sends a command/query and the ECL
controller respond to this. Do not attempt to send new commands before a response is received or the timeout expires.
In a Modbus network it is not possible to send commands/queries to different devices at the same time (except broadcast). One
command/query – response must be completed before the next can be started. It is necessary to think about the roundtrip time
when designing the network. Larger networks will inherently have larger roundtrip times.
If multiple devices must have the same information, it is possible to use the broadcast address 0. Broadcast can only be used
when no response is necessary, i.e. by a write command.
The network must always be configured as a daisy chained network, see the three examples from a very simple network to more
complex networks in section ‘Network layout’.
Danfoss District Energy VI.LG.V3.02 DEN-SMT/DK
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