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Upgrade to Citect 2018 ABCLX redundancy problems

Peter

We are in the middle of upgrading to 2018 from V7.2 and cannot get the IO servers that use ABCLX drivers to be redundant. If the primary is on and the standby is off data shows on screen just fine. Then when the standby is turned on the points all go to #BAD or #PEND (off and on, occasionally data does come in but then goes right back to bad/pend) . This also occurs if the primary is off and the standby is on and then the primary gets turned on. Does anyone have any suggestions for us to try?

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  • Hi Patrick,
    The ABCLX driver is different to standard drivers. The standby IO Device subscribes all tags to the PLC, since it takes a lot of time to download tags from the Controller, check what tags are configured, build optimised blocks that contain the tags, then subscribe to each block of tags. It then sits in a warm standby mode, polling the same tags, but at a very slow rate. So that when it does need to become primary or active, it has all the information it needs and can start polling fast instantly. See TN 6209 for how ABCLX goes online. The Watchdog=0 parameter might have a negative effect for the ABCLX device. It is also very common for the Control Logix platform to accept more than one "master" request. It is fully supported. The only limitation is the available CPU bandwidth available to servicing communications (this is available to fine tune as required using PLC programming software).
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  • Hi Patrick,
    The ABCLX driver is different to standard drivers. The standby IO Device subscribes all tags to the PLC, since it takes a lot of time to download tags from the Controller, check what tags are configured, build optimised blocks that contain the tags, then subscribe to each block of tags. It then sits in a warm standby mode, polling the same tags, but at a very slow rate. So that when it does need to become primary or active, it has all the information it needs and can start polling fast instantly. See TN 6209 for how ABCLX goes online. The Watchdog=0 parameter might have a negative effect for the ABCLX device. It is also very common for the Control Logix platform to accept more than one "master" request. It is fully supported. The only limitation is the available CPU bandwidth available to servicing communications (this is available to fine tune as required using PLC programming software).
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