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TOP Server support for Siemens S7 Redundant Controllers

Does the TOP Server Siemens S7 TCP Ethernet driver support the redundant CPU models, such as S7-400H and S7-400FH?

The TOP Server Siemens TCP/IP Ethernet driver does support the redundant models, since they are members of the S7-400 “Family”, which are supported by this driver.  The “H” CPU is the hot swappable CPU used in Redundant configurations.   The “FH” is the fail-safe version of the same.  They are S7-400 models with the special features for redundancy not affecting the memory map of the addresses that we would need to access.  They are supported under the category of “S7-400" device model.

For Redundancy Control of CPUs:

Starting with TOP Server V4.300.449 and newer, when you configure a device in TOP Server for an S7-400 or S7-300 model, two special internal tags are automatically made available to client applications specifically for each device:

  • _Rack - corresponds to the number of the rack in which the CPU of interest resides
  • _Slot - corresponds to the number of the slot in which the CPU of interest resides

These internal tags are writable from your client application so that the CPU being accessed is changeable at runtime.  Changing either of the internal tags re-establishes the connection to the new CPU specified.

To make the maximum usage of this capability, there is also an _Error system tag that can be used to detect communications failure with the currently specified CPU.  By monitoring this system tag, on detecting a failure, if your client application allows for scripting writes, a write to the _Rack and _Slot tags would cause failover to the redundant CPU.