Sekedar sharing …
Lagi baca-baca tentang PLC-5 redundant dimana memakai module BCM dan atau BEM.
BCM dan BEM ini infonya sudah obsolete dari OEM, jadi kalau masih menggunakan module ini harus secepatnya upgrade ke controllogix.
Atau mungkin ada rekan2 yang coba ganti BCM dengan module/metode lain sehingga masih bisa mempertahankan existing konfigurasi PLC-5?? Silahkan di share..
Sumber: 1785-um524_-en-p-PLC-5 Backup Communication Module
Berikut cuplikannya … (Terjemahin sendiri yah)
Redundant Processor dengan BCM
Redundant Processor, BCM, BEM
Terms and Conventions
- HSSL is the 1785-BCM module’s High-Speed Serial Link. It is a dedicated communication link between the primary and secondary 1785-BCM modules and is used to pass I/O, status, and data table information.
- Primary System is the PLC-5 processor that controls the I/O and the other equipment associated with that processor.
- Secondary System is the PLC-5 processor that is ready to assume control of the I/O and the equipment associated with that processor.
- Backup System is the primary and secondary systems.
- Switchover is the transfer of I/O control from the primary processor to the secondary processor.
- Bumpless switchover is the transfer of I/O control from the primary processor to the secondary processor where the operation of the process being controlled is not affected.
- Asynchronous processing is processing where the ladder program scan and the block-transfer scan operate independently of each other within the same scan time.
- BTW is block-transfer write; transfer of up to 64 words from the processor to the block-transfer module.
- BTR is block transfer read; transfer of up to 64 words from the block transfer module to the processor.
- Smart Switch Interface is a remote I/O interface in the 1785-BCM module that responds to secondary scanner poll commands with actual input values from the remote I/O link, making the scanner think it is talking with remote I/O.
Why Use a Backup System?
The objective of any redundant system (backup system) is to improve the amount of up-time of a machine or process by ensuring consistent availability of that machine, and by reducing costs associated with equipment failure. By using this backup system, you can guard your application against shutdowns caused by the programmable controller.
The backup option is used where you must transfer the control of the process to a secondary system, without thereby interrupting the machine/process operation.
To guard against system shutdown, a backup system must provide:
- equipment with exceptional reliability
- automatic fault isolation
- minimal disturbance of the process when switching from the primary to the secondary system
A PLC-5 system configured with 1785-BCM modules provides high speed backup communication and switchover of the Data Highway Plus and remote I/O links.
How the PLC-5 Backup System Works
In the PLC-5 backup configuration, one system (consisting of one PLC-5 processor, 1785-BCM module, power supply, and chassis) controls the operation of the remote I/O. This system is referred to as the primary system.
The other system is ready to take control of the remote I/O in the event of a fault in the primary system. This is referred to as the secondary system.
The PLC-5 backup system does not back up local I/O; therefore, do not install I/O in the local chassis.
During normal operation, the primary system sends remote input and data table data to the secondary system so that in the event of a switchover, the secondary system (which becomes the new primary system) has the same data.
Remote I/O data is automatically transferred over the High-Speed Serial Link (see Figure 1.1). This transfer is independent of the application program.
Data table values are transferred from the primary to the secondary system with block transfer instructions that you include in your ladder program.
You do not have to transfer data table values if not necessary for your application.
Figure 1.3 shows how data table data is transferred from the primary to the secondary system.
Should a fault occur in the primary processor, control switches to the secondary system in less than 50 ms (maximum).
When a switchover occurs, the outputs in the remote I/O maintain their last state until they come under the control of the secondary processor.
Backup Expansion Module
The 1785-BEM is the backup expansion module for the 1785-BCM series B module. It has the capability of switching two additional configurable communication channels when you are using a 1785-BCM series B module with a PLC-5/40, -5/60, or PLC-5/80 processor.
sisanya baca saja di manualnya yah … bisa di download dengan searching di mbah google…
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