volatile to non-volatile, any controllers ?

[2Faced]

Hello All-

I have a project which my client wants to change the set points when the PLC is still online. In my program the set points are stored in flash and then called to the registers upon controller booting, I can alter the registers to change the set points when the controller is online, but after a power cycle everything is back as flashed. My controller does not support flash/non-volatile memory manipulation and my client doesn't want to use an addon battery pack.

I am wondering if there are controllers (from any vendors) that support flash memory manipulation ? Any recommendation would be grateful.

Thank you.

 

[PreLC]

What type of a PLC are you using? Usually PLCs don't have loss of cycle power as they have internal batteries which act as backups for volatile memory.

AB, Siemens, Beckhoff etc. all PLCs have this feature.

 

[2Faced]

Hi PreLC, I am using a Rx3i CPE330. To save all RAM upon power down an energy pack will be needed. Unfortunately this solution is not preferred and this model doesn't support flash/non volatile read/write.

There is another topic discussed about this: http://www.plctalk.net/qanda/showthread.php?p=736407

 

[Steve Bailey]

What is the firmware version of your CPU? According to the help files, SVC_REQ code 57 (Write to non-volatile memory) is supported for firmware version 6.00 and higher.

SVC_REQ 57 specifies a range of reference addresses to read from a running PACSystems CPU and write to nonvolatile storage. This functionality is intended to retain a limited set of values, such as set points or tuning parameters, that need to change when the PACSystems is running.

 

[2Faced]

CPE330 firmware version 10.15 still doesn’t support service request 56,57.
This is what I have from the IPI:
“The IC695ACC402 Energy Pack automatically saves all user memory to flash when the CPE330 is powered off, and restores it to RAM when the CPE330 is powered on. Consequently, the CPE330 does not support Service Requests 56 & 57 Logic Driven Read/Write to Flash. The ENO output of the function block returns no power flow if these service requests are executed.
When migrating a CPU320 application that uses Service Requests 56 & 57 to a CPE330, the IC695ACC402 Energy Pack needs to be attached”

 

[dYoast]

Check the settings of your CPU. You may want to change "Data Power-up Source" to "Conditional Flash" or "Always RAM".

I have programs with initial values that are stored in flash. Users can change values via an HMI. On power cycles, the changed values are retained. My CPU is set to "Conditional Flash"
This is on an Rx3i CPE305, but I do have the energy pack.

 

[2Faced]

Thank you all for your comments. Maybe I should try to convince my client to reconsider the energy pack option.

 

[Steve Bailey]

What response do you get when you attempt to execute a SVC_REQ code 57?

 

[Steve Bailey]

OK, here's what I found in the manual GFK2942X.

The IC695ACC402 Energy Pack automatically saves all user memory to flash when the CPE330 is
powered off, and restores it to RAM when the CPE330 is powered on. Consequently, the CPE330
does not support Service Requests 56 & 57 Logic Driven Read/Write to Flash. The ENO output of
the function block returns no power flow if these service requests are executed.
When migrating a CPU320 application that uses Service Requests 56 & 57 to a CPE330, the
IC695ACC402 Energy Pack needs to be attached.

So that option is out for your case.

Is there an HMI and/or a historian included your system? If so, you might be able to write a script in the HMI to do what you need to do.

 

[Steve Bailey]

And I see that I should have paid closer attention to all of the posts in the thread. The OP posted the same quote.

I have two used IC695ACC402-AB gathering dust in my closet. The OP can contact me and we can dicker over price and shipping.

 

[2Faced]

Thanks Steve.

Update: Emerson tech support replied that service requests 56, 57 will never be supported on the CPE330. However they just released a new SVC_REQ 63 in FW 10.80 allowing writing entire ref table to flash (GFK-2950K section 6.34):

6.34 SVC_REQ 63: Logic Driven Write of
Reference Memory
This Service Request is supported on the CPE330 only. However, when a CPU is
configured for Hot Standby Redundancy, this Service Request will not be available.
PACSystems controllers support four storage locations in nonvolatile memory,
which can be written to or deleted by this Service Request. Each storage location
can hold an arbitrary length of reference memory data from the %AI, %AQ, or %R
reference tables, up to the maximum table size configured in PAC Machine Edition.
This data is restored to the reference tables at power-up after initial values have
been established, but only if the data in RAM was not preserved over the power
cycle. If RAM was preserved none of the data in the four storage locations is
restored. Refer to the %S0055 system bit or the Audit Trail to determine if any
reference table data was restored at power-up.
When the data is copied to Reference memory, it is done in order of Storage
Location number, beginning with location 0. Therefore, if the stored data comes
from overlapping references, the data with the higher Storage Location number
will overwrite the data with the lower Storage Location number.