ProSoft ProLinx 104S, Руководство по протоколу

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IEC-60870-5-104 (104S) Protocol Implementation 104S ♦ ProLinx Gateway
Protocol Manual (Firmware v3.00 and later)
Page 104 of 157 ProSoft Technology, Inc.
January 22, 2010
3.8 Redundant Connections
The module supports redundancy by accepting two simultaneous client connections.
Only one connection can send/receive user data at a time, so the module uses the
STARTDT function to select to which client it will be exchanging data. The module
will send events and accept commands only to the client connection that has sent
the last STARTDT function.
The following diagram shows an example where the module sends five events to two
different clients. The module initially receives a STARTDT request from Client 1 and
therefore sends the following events to this client. After the third event the Client 1
sends a STOPDT request and then Client 2 sends a STARTDT request to the
module. From that point on the module will send the next events to Client 2 only.
Please note the following:
1 The STARTDT triggers the switch of the connection. Therefore, the STOPDT
request is not actually required from the current client to perform the switch
(although the previous diagram indicates the recommended communication
procedure)
2 The module will respond to any TESTFR requests received by both clients at any
time.
By selecting the E key (Display Program Status) the user can monitor the status of
both connections can be monitored. For the example below, the client connected
through Socket 1 is actively exchanging data to the module. This can be confirmed
since the START DT Active register has a value of YES (which means that the last
START DT received was through Socket 1).