RTP Corporation, represented by PLC Peripherals , has introduced the Micro 2008R HCS, a redundant version of the Micro 2008 HCS, fully supported by RTP NetSuite. Its hybrid design provides both the high-speed scanning features of a programmable logic controller (PLC) while simultaneously supporting the complex control algorithms found in a distributed control system (DCS).
The Micro 2008R HCS hot standby solution ensures essentially zero downtime through the use of two parallel controllers, power supplies, backplanes, network interfaces, and I/O option cards. Bumpless switchover and non-intrusive reinitialisation are controlled by its advanced design.
The Micro 2008R HCS consists of two embedded processors, two power supplies and two chassis backplane assemblies. It can communicate with any Windows 2000/NT platform or with another Micro 2008, Micro 2016, RTP 2300 or RTP 2000/2200 node.
Each mini chassis accommodates eight RTP I/O cards. This mini chassis uses the same power supply as all the other RTP 2300 family chassis. The Micro 2008R supports the same set of front-panel RTP I/O cards used in the RTP 2300 systems.
One mini chassis operates as the active primary and the other operates as a hot standby secondary. The processor in the secondary monitors the health of the system and automatically transfer control from itself to the secondary (hot standby) processor if an error is detected.
Upon completing switchover, the secondary assumes primary status, and the failed unit is marked as being unavailable.
Parallel controllers provide the Micro 2008R HCS with redundant intelligence. While only the primary processor is responsible for communications with the host, the secondary processor executes its own copy of the control application and monitors the communications between the host and the primary.
If the secondary processor receives more messages than the primary, a communications failure between the host and the primary is assumed. The secondary will initiate a switchover and take over the role of primary controller.
Watchdog Timers (WDTs) in the I/O cards are used to monitor communications with the primary processor. If an I/O card WDT timeout occur, it indicates that the primary processor has stopped scanning because of a failure or because it has been powered off.
This condition will initiate a switchover to the secondary processor, which resumes the I/O scanning and host communications.
Switchovers can also be initiated by the NetArrays TND hot standby switchover command, which is controlled by a special target node directive variable within the project program.