Using a memory card as a removable storage unit for data logging.

I never used MMC as removable memory units, and I even don't know if it's possible.

So far, reading manuals and doing some test, I see that I can use a MMC as a transfer unit, to load a new or updated PLC program from the MMC into the CPU load memory.

Or I can use the MMC as a load memory itself, that will be used INSTEAD of the CPU internal one. In this latter case I can't remove the MMC from the CPU otherwise the PLC would be dead, without load memory and thus without program.

So image now that I want to log some data into the MMC, using the datalog set of instructions (Create, Open, Write, Close...). 

The manual says that I can read datalogs files from the web server. Or that I can pull the MMC out from the CPU, that will then go into the stop state. The I'll be able to read the MMC datalog files putting the MMC into some Windows PC. 

But that means that:

• I can't get datalog files on my PC, extracting the memory card, without stopping the CPU.
• I can't swap a full MMC with an empty one, unless I put the PLC program also into the new empty MMC.

No way to use the MMC as a normal removable device?

Hi salrandazzo,

What you are saying is correct..im too wondering how can i take my logs without stopping my plc if i dont have web server access..

1. if u remove the memory card from the cpu ,cpu will not have the program because memory card acts as the internal memory..

2.new memory card needs program else your cpu remains a new one with no program blocks.

BALAKRISHNAN92

Hi salrandazzo,

What you are saying is correct..im too wondering how can i take my logs without stopping my plc if i dont have web server access..

1. if u remove the memory card from the cpu ,cpu will not have the program because memory card acts as the internal memory..

2.new memory card needs program else your cpu remains a new one with no program blocks.

 Hi  BALAKRISHNAN92

this problem can be solved by using a comfort panel.
I have a doble need:
- I've to send historical data via modem, on remote request
- The customer wants to get data on a removable medium.

So I'm planning to store data on the SD card by not using datalogging. I'll write data on an unlinked DB using WRIT_DBL instruction. On remote request I'll get my data using READ_DBL instruction. On this purpose I wrote a demo progam that is available here.

But what about exporting data on a removable media? My colleague told me that a comfort panel has the possibility to log data on its own memory, and then copy files on a USB memory stick. That's what I'm planning to do. I'll publish it when ready.

Hi,

what u are saying is possible ...but y to  log data in PLC then again in HMI?? We can directly log in SD card of HMI using script in CSV or xlsx format..

thank you its good info

BALAKRISHNAN92

Hi,

what u are saying is possible ...but y to  log data in PLC then again in HMI?? We can directly log in SD card of HMI using script in CSV or xlsx format..

thank you its good info

 I have double purpose:

1. I have to log data into PLC so that I can retrieve those data by program and send them on the phone line via modem.
2. I have to log data into HMI so that the user can insert its USB memory stick and collect data to take them away.

I didn't find any other way to satisfy this double requirement.

Hi salrandazzo,

is it possible to retrieve log datas in plc using program ??

its great can u pls share the program.

0_Einstein

The Memory card slot in the s7-1200 is not a normal removable card slot.

It has several functions, some of which are mutually exclusive as you already noticed.

Inserting and removing the MMC from a running PLC can definitely cause unintended process disruption.  For that reason, if you choose to use MMC for load memory and also attempt to read/write datalogs, you will definitely want to enable the web server so you can extract the data from the memory card without card removal.

I hope this helps.

salrandazzo

I never used MMC as removable memory units, and I even don't know if it's possible.

So far, reading manuals and doing some test, I see that I can use a MMC as a transfer unit, to load a new or updated PLC program from the MMC into the CPU load memory.

Or I can use the MMC as a load memory itself, that will be used INSTEAD of the CPU internal one. In this latter case I can't remove the MMC from the CPU otherwise the PLC would be dead, without load memory and thus without program.

So image now that I want to log some data into the MMC, using the datalog set of instructions (Create, Open, Write, Close...). 

The manual says that I can read datalogs files from the web server. Or that I can pull the MMC out from the CPU, that will then go into the stop state. The I'll be able to read the MMC datalog files putting the MMC into some Windows PC. 

But that means that:

• I can't get datalog files on my PC, extracting the memory card, without stopping the CPU.
• I can't swap a full MMC with an empty one, unless I put the PLC program also into the new empty MMC.

No way to use the MMC as a normal removable device?

 

interseting

thanks