Flash memory in 400-H / PCS7 CPU

It has been noted the memory for 400-H CPU / PCS7 CPU are RAM by default / in configuration tools and "already assembled / tested". There is no option for Flash memory. This cause inconvenience for installation for "marine or even offshore rigs" industry whereby Flash memory is always preferred. The reason is that the engineers on board are always on and off in short term therefore in most of cases they are not properly trained for how to replace back-up battery without lost of project data in RAM, not to mention the reloading of project program in case of it is lost from RAM.

In the case of marine, this could mean a great danger while a ship is sailing on a open / rough sea when a critical system malfunction due to program lost in the RAM.

A week ago, one of major drilling rig company experienced program lost for a critical system on the rig, due to RAM configuration causing painful dollars lost.

Suggestion: Flash memory be added as option in configuration tools and also to be "pre-assembled and tested" when the application calls for.

Hello gqhuang,

I truly understand your situation (Same complaint from few of my customers).

I'm not a PCS7 expert but there's a possibility to use FLASH memory as long as you don't have 410CPU.

You will have to accept the fact that online modifications are not possible without STOP.

Process Control System PCS 7 Tips and Tricks

Implementation:

You only use FEPROM memory cards when the user program no longer changes or only very seldom changes and you want to store the data permanently. The stored user program remains on an FEPROM memory card even if you remove the card from one AS and slot it into another AS.

Notice

Note, however, that there are programs that change the user structure on the load memory without loading. For example, the application "Route Control" is used in breweries. This application changes the length of data blocks in the load memory.

If you use FEPROM memory cards here, then the program can no longer function.

The PCS7 is mainly a DCS. The main target is processes that work 24/7/365 and may require frequent change. It should be a piece of cake to add a PID loop for example in few minutes and download without disturbing operation because STOP for a change in such applications is not acceptable at all.

I understand that marine applications do not require frequent change. So, it should be no problem if you use FLASH memory as long as you don't have the latest 410 CPU.

For CPUs V6.X (e.g. 6ES7414-5HM06-0AB0) the load memory is expandable with FLASH.

While for the new 410 CPU (which is going to be the core of PCS7), you can't use FLASH as the load memory is not expandable at all.

Best regards,

H-H

Yes FLASH is more advantangeous than volatile RAM. But 

How RAM is losing backup while you are replacing battery.  Battery replacement with Main power supply ON is the recommended way to replace. If your application is critical keep redundancy at PS level OR replace batteries as a PM.

Vijay

Hi gqhuang

I totally agree with your request and I also accepts H-H reply,but I have some concerns on your case:

1) As you mentioned that there is a critical S7-400H system running with PCS7 so there is at least 4 back-up batteries (the installed Power supply must be at least 10Amp. * 2  which requires 2 batteries in each one)

2) For a PCS7 project there is a self test from time to time, regarding the back-up batteries, if there is any faulty battery from the four installed batteries you will get an error message on the workstation.

3) you need at least 1 back-up battery healthy to change the other faulty batteries.

4) For a marine offshore rigs there must be well trained specialist that knows essentials of this critical system, how to keep it alive without losing control.

gqhuang

It has been noted the memory for 400-H CPU / PCS7 CPU are RAM by default / in configuration tools and "already assembled / tested". There is no option for Flash memory. This cause inconvenience for installation for "marine or even offshore rigs" industry whereby Flash memory is always preferred. The reason is that the engineers on board are always on and off in short term therefore in most of cases they are not properly trained for how to replace back-up battery without lost of project data in RAM, not to mention the reloading of project program in case of it is lost from RAM.

In the case of marine, this could mean a great danger while a ship is sailing on a open / rough sea when a critical system malfunction due to program lost in the RAM.

A week ago, one of major drilling rig company experienced program lost for a critical system on the rig, due to RAM configuration causing painful dollars lost.

Suggestion: Flash memory be added as option in configuration tools and also to be "pre-assembled and tested" when the application calls for.

 As you mentioned marine applications are very critical and should not be down even for a second.

While having a Flash may help, it has some disadvantages though:

• If both the master and standby CPUs fail, you will have to wait for like 10 minutes till both systems reboot again. This is not the case with RAM+battery
• If both the master and standby CPUs fail, all the data stored in the datablocks will be replaced with initial values. (this may be a big problem, as we are talking about PID tuning, Setpoints and alarm limits)
• If both the master and standby CPUs fail, you will lose any changes not transferred using the option "download user program to memroy card", or "copy RAM to ROM".

On the other side, as Khaled mentioned, you can protect your system from going down by having redundant power supplies, each with 2 batteries. You can have 4 power supplies and 8 batteries and this is enough for a lifetime.

There is a saying: "if it works, don't fix it" which is the way using RAM+batteries as it keeps it working versus Flash which will initialize your system if it goes down.

With Firmware v8.2 of CPU 410-5H all load memory became ROM. You also can load changes. You can update CPU just via install new FW version.

See there: https://support.industry.siemens.com/cs/ww/en/view/109476571