ALTUS Nexto Series User Manual

6. REDUNDANCY WITH NX3030 CPU
Direct Variable
AT Variable
DG_NX4010.tRedundancy
.RedDgn-
Loc.sGeneral_DiagExt.*
Description
Variable Bit
2..7 (Occulted reserved bits)
Bits reserved to future use. They aren’t
shown at the symbolic structure (hidden).
%QB(n+50) - abyReservedBytes[1..5]
5 reserved bytes to future use. They aren’t
shown at the symbolic structure (hidden).
Table 213: General Redundancy Diagnostics, Extended Part
6.6.4.2. Redundancy Commands
The structure command fields RedCmdLoc and RedCmdRem have a suffix which can be Local or Remote. E.g. there are
the command fields StandbyLocal and StandbyRemote that have equivalent effect to the PX2612 panel STAND-BY button.
A command with Local suffix generated in RedCmdLoc must be executed in the local PLC (local). On the other hand, a
command with Remote suffix generated in RedCmdLoc will be executed in another PLC (remote). This works as the following:
The remote PLC, each MainTask cycle, receives the RecCmdLoc copy from the local PLC through NETA / NETB, and
this copy is called RedCmdRem in it
The remote PLC only executes the RedCmdRem commands with the Remote suffix
Example 1: if the local PLC is in Active state, and it’s desired to switch it to the Stand-by state, the DG_NX4010.tRedundancy
.RedCmdLoc.bStandbyLocal bit can be turned on in it.
Example 2: if the remote PLC is in Active state, and it’s desired to switch it to the Stand-by state, the DG_NX4010.tRedundancy
.RedCmdLoc.bStandbyRemote bit can be turned on in the local PLC. This may be useful, for instance, if the communication
of a SCADA system is temporarily unavailable with the remote PLC. In this case, the command is written by the SCADA in
the local PLC that retransmits to the remote PLC through NETA / NETB.
ATTENTION
If the DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.bExchangeSync diagnostic is
indicating a Diagnostics and Commands Exchange service failure, a command with Remote
suffix isn’t allowed to be transmitted to the remote PLC, thus, won’t be executed.
To trigger a command, the RedCmdLoc correspondent bit must be turned on. This can be done through a SCADA system,
executing writing via MasterTool or even turning the bit on inside a POU as ActivePrg or NonSkippedPrg.
The user doesn’t need to worry with the command bit deactivating, which is automatically done by the redundancy man-
ager:
In case of commands executed in the local PLC (RedCmdLoc + commands with Local suffix), the bit is turned off as
soon as the command is seen and executed
In case of commands executed in the remote PLC (RedCmdRem + commands with Remote suffix):
• In the remote PLC, the command is executed when the redundancy manager sees an up-going edge in the command
bit
• In the local PLC where the command was generated, the bit is turned off automatically in the next MainTask cycle
ATTENTION
There are two command bits which normally must be turned off by
the user: DG_NX4010.tRedundancy.RedCmdLoc.bTestModeLocal and
DG_NX4010.tRedundancy.RedCmdLoc.bTestRelayLocal. Further details regarding
these commands are described ahead in this section. In case the user forgets to turn them
off, there are automatic mechanisms which are supposed to do it instead.
It’s important to stress that any command activating or deactivating are registered in the Redundancy Event Log, which is
important for the history analysis, e.g. to determine a switchover cause.
Next, the RedCmdLoc and RedCmdRem structure fields are defined:
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ALTUS Nexto Series Specifications

General

Brand	ALTUS
Model	Nexto Series
Category	Computer Hardware
Language	English