SD Card status => CODESYS?

CODESYS
1

My end goal is to create / trigger an alarm to tell the user there is an issue with controller’s SD Card, because we are writing CSV logs there.
I am worried about a situation where an SD card is not present (or has failed) and we automatically start writing the logs directly to the controller without anyone realizing.

Using a CC100 controller, when I CAA.File.Write to ‘/media/sd/Logs/’ without an SD card, the controller will create a directory locally under that path. This does not cause the File.Write FB to throw an error.
I could probably have Node RED inspect the /proc/mounts file but don’t want to add another layer if I do not need to.

Is there any way for the controller to tell CODESYS if it can see or write to the SD card?

2

You can use WagoSysFileDir Library to check for a directory on the card.

VAR

eSdExist : WagoSysFileDir.eResultCode;
eSysConfigExist: WagoSysFileDir.eResultCode;

END_VAR

eSdExist := CheckDirectoryExists('/media/sd/logs');
eSysConfigExist := CheckDirectoryExists('/media/sd/sysConfig');

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3

VAR
myFBConfigTool : FbConfigTool;
sSDresult : STRING(255);
xSDexecute : BOOL := FALSE;
xSDresult : BOOL := FALSE;
END_VAR

IF xSDresult = FALSE THEN
myFbConfigTool( xExecute := xSDexecute, // Start the call once
sCallString := ‘./get_filesystem_data medium-list-json’, // Get the order number of the controller
sResultString => sSDresult // Get the result
);

IF myFbConfigTool.xDone THEN 												
	xSDexecute := FALSE;

	IF myFbConfigTool.xError = FALSE THEN	
		IF sSDresult = '[ "sd-card", "internal-flash-emmc" ]' THEN
			xSDresult := TRUE;												// SD card inserted
		ELSIF sSDresult = '[ "internal-flash-emmc" ]' THEN
			xSDresult := FALSE;												// No SD card inserted
		END_IF
	END_IF
END_IF

END_IF
4

The solution MikePsaltis provided does work for my specific situation, but I’ve been using ketan’s solution for the past week and I like it more.

ketan’s solution is more flexible and answers the broad question: “Does the system recognize an SD card?”, and does not depend on the ‘logs’ directory existing.
IF I have an SD card, THEN
I can create the ‘logs’ directory,
and then check if that directory creation step was successful using MikePsaltis’ solution.

5

Personally I’ve done another solution which is making a symlink:

ln -s /media/sd/ /home/codesys/PlcLogic/sd

This enable me to use the folder /home/codesys/PlcLogic/sd as my SD card and I have an error if it doesn’t exist and the link is broken since it can’t crate the folder.

6

I also like ketan’s approach but found two issues with this specific bit of code:

On some controllers the result string can be somewhat different: “internal-flash-nand” instead of “internal-flash-emmc”. I have seen this in an e!Cockpit project. It can be related to older firmware versions or older controller models.

Related: the above code snippet has logic for two resulting strings: it can be either ‘[ “sd-card”, “internal-flash-emmc” ]’ or ‘[ “internal-flash-emmc” ]’ . Logically there must also be a third option, where the sSDresult string has neither value. In that case no value gets assigned to xSDresult. In other words: xSDresult stays at the value it had before the code was executed. This is neither elegant nor robust.