Best way to handle MMC's on S7-300 cpu's to do program updates

[smf]

Hi there.

I need to do a really small update to a program in a s7-314 cpu and wonder what's the best way to do it?

The machine is located far away from me and a modem connection is not an option in this case so i would like to use a MMC.

I have the same type of CPU here at my desk that i could use to do the transfer to the mmc but i don't really know how to handle the MMC's.

Can i transfer the program to a MMC and then just send it away to the customer and let them install it. and what about the parameters in the DB's.. will they be lost? can i hotswap the MMC or must the PLC be powered off? etc

 

[Imi'ike]

This is the procedure I send with a program update on a MMC to our customers. It works for me.

1. Turn off the power to the PLC
2. Remove the old MMC from the PLC.
3. Insert the new MMC into the PLC.
4. Return power to the PLC.
5. Wait for the processor to “boot”. This takes a few seconds and is indicated by the flashing yellow LED labeled STOP. The process is complete when the yellow STOP light stays on.
6. Push the toggle switch down and hold it in the MRES position, until the “STOP” light flashes a couple times, and then remains steady again.
7. Release the toggle switch.
8. Push the toggle switch up to the RUN position. The RUN light should blink green for a short period of time, and then turn on solid green. The SF (system fault) and BF (bus fault) LEDs should turn off.

This works for me. But in reply to your question about power, yes, I have them remove power. As for the data in the DBs, this method uses a memory reset, so all that data will be lost. I get around this by storing data to recipes on an HMI. Perhaps someone else has a method that will work better for you and your DB data.

 

[John Gaunt]

Preserve DB Data

I use S7-400 CPU's with Flash Memory Cards. I use the following procedure to Upload / Download to ensure all my setpoints, limits, PID values etc are in the DB's stored on the Flash Card. I understand that the same proceedure will work for S7-300 MMC's. I have been informed that I should power off the PLC whilst changing cards and will do so in future although I have had no problems "hot swapping" Flash Cards.

1. Put all control loops on BACKUP.

2. Open empty Step7 project eg TEST.

3. Upload PLC program from required PLC including Setpoints etc to project TEST. (PLC \ Upload Station to PG)

4. If Flash Memory Card already installed then go to 9.

5. Stop PLC with switch on CPU module.

6. Insert Flash memory card (EPROM).

7. Do memory reset on PLC module and put back in RUN.

8. If the PLC will not run or Profibus communications cannot be established it will be necessary to download the System Data via the PC Adaptor. (Make sure that it is selected in Set PC/PG Interface)

9. Select S7 Program / Blocks and then select Edit / Select All (to include System Data)

10. Do PLC \ Download User Program to Memory Card.

PLC will have the program loaded to the Flash card with setpoints intact. In the event of a power failure at the CPU (Batteries dead or removed) The Program will be re-loaded from the Flash Card when the CPU is restarted.

 

[John Gaunt]

Somebody must have a simpler way to backup the DB data.