Frequently Asked Question

The drop down menu for choosing a logic solver does not include the HIMA SELLA HiQuad H51q, is there a particular reason for this, and is it possible to input the information for this system manually?
Last Updated a year ago

The HIMA PLCs are indeed not listed in the exida SERH. HIMA simply do not provide us permission to do so. Our only hope in changing that is to get our users to put pressure on HIMA to get the systems in the software. An easy work around is to select a generic SIL 3 certified PLC. This represents a conservative estimate of a SIL 3 PLC, which should adequately cover the HIMA PLC that you are looking at.

If you wish to enter the HIMA failure rates as they are provided to you can indeed use the "user defined" logic solver.
There are 2 options to implement this:
1. Simple
2. Advanced

@1. Combine the failure rates of the various parts that are included in your logic solver, specify these as 1 set of failure rates and then set the maximum number of I/O connections (default is 1 DI and 1 DO). Through the "+" you can however add more. You will also need to select the "calculation model". If memory serves me right, the HIMA system works in a 1oo2D fashion.

@2. You can specify failure rates for each module separately. This is a similar approach, as above but now you specify many sets of failure rates. I have attached a short video showing this.

PTC stands for Proof Test Coverage. This represents the percentage of dangerous failures that you can reveal when you do a proof test. I do not see this information on the HIMA datasheet. I do see a statement that the proof test interval is 10 years. If HIMA is suggesting that you use 100% for the proof test coverage at 10 year, than this is the same as assuming that after 10 years you completely replace the system with a new system.

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