How to log data in a .csv file

STM32CubeMonitor saves logged data in a .stcm file. This format allows:

• Direct data import into an STMicroelectronics chart
• Data file recovery in an other flow

Nevertheless, some manipulations are possible with a .csv file and not with a .stcm file, such as:

• Analyze data easily when a data issue occurs
• Open the .csv file in a spreadsheet editor
• Share the data with other users

There are two solutions to get a .csv file:

• Convert the .stcm file to the .csv format
• Export data directly into a .csv file from the flow

Both options are described in this wiki. Users must select the solutions that best fit their applications.

1 Convert a .stcm log file into a .csv file

It is possible to convert the generated .stcm log file into a .csv file to manage the data more easily.

1.1 Import the flow

Import the following flow into the STM32CubeMonitor workspace:

[{"id":"34072f28.a29b6","type":"tab","label":"Convert .stcm to .csv ","disabled":false,"info":"This flow is used to convert stcm file in csv file\n\nThe file name must be entered in the \"set file name\" node\n\nThe csv output format is variable Name, x, y\nNote : the data may be processed by group, so the x value may not be in time order. The csv file may be sorted on the x value to ensure order coherency. "},{"id":"5442c1fe.bae16","type":"subflow","name":"Group variables in a .csv file","info":"","category":"STMicroelectronics","in":[{"x":60,"y":80,"wires":[{"id":"76ed82a.aeea47c"}]}],"out":[{"x":840,"y":360,"wires":[{"id":"e2840a46.67f638","port":0}]}],"env":[{"name":"nbVar","type":"num","value":"","ui":{"icon":"font-awesome/fa-cogs","label":{"en-US":"Number of Variables"},"type":"input","opts":{"types":["num"]}}},{"name":"delete_time","type":"bool","value":"false","ui":{"icon":"font-awesome/fa-clock-o","label":{"en-US":"Single Time"},"type":"input","opts":{"types":["bool"]}}}],"color":"#3CB4E6","icon":"node-red/join.svg"},{"id":"4eb816e2.08f228","type":"function","z":"5442c1fe.bae16","name":"Associate values with same timestamp","func":"let i = 0;\nlet j = 0;\nlet n = 0;\nlet msg1; \nlet msgArray = new Array();\nlet nbVar = msg.payload.length;\n\nfor(i = 0; i < nbVar; i++){\n    \n    let underArrayLength = msg.payload[i].length;\n    \n    for(j = 0; j < underArrayLength; j++){\n            \n            for(n = 0; n < nbVar; n++){\n                msg1 = msg.payload[n][j];\n                msgArray.push(msg1);\n            }\n    }\n    msg.payload = msgArray;\n    return msg;\n}","outputs":1,"noerr":0,"x":650,"y":80,"wires":[["3090a095.2eb79"]]},{"id":"3090a095.2eb79","type":"split","z":"5442c1fe.bae16","name":"","splt":"\\n","spltType":"str","arraySplt":"${nbVar}","arraySpltType":"len","stream":false,"addname":"","x":870,"y":80,"wires":[["9d83ccf1.3555"]]},{"id":"f131f71e.41cae8","type":"function","z":"5442c1fe.bae16","name":"Format data","func":"let output=\"\";\n\nif(typeof msg.payload == 'number') {\n    output = msg.payload;\n    \n}else if(typeof msg.payload == 'string'){\n    output = msg.payload;\n}else{\n    output = msg.payload.x + \";\"+ msg.payload.y;\n}\n\nmsg.payload = output ;\n\nreturn msg;","outputs":1,"noerr":0,"x":790,"y":200,"wires":[["e2840a46.67f638"]]},{"id":"e2840a46.67f638","type":"join","z":"5442c1fe.bae16","name":"Join consecutive messages from the number of monitored variables","mode":"custom","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":";","joinerType":"str","accumulate":false,"timeout":"","count":"${nbVariables}","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":380,"y":360,"wires":[[]]},{"id":"76ed82a.aeea47c","type":"join","z":"5442c1fe.bae16","name":"Join [nbVar] consecutives messages","mode":"custom","build":"array","property":"payload","propertyType":"msg","key":"topic","joiner":";","joinerType":"str","accumulate":false,"timeout":"","count":"${nbVar}","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"num","reduceFixup":"","x":290,"y":80,"wires":[["4eb816e2.08f228"]]},{"id":"9d83ccf1.3555","type":"function","z":"5442c1fe.bae16","name":"Delete duplicate timestamps if user wants","func":"let i;\nlet delDup = env.get(\"delete_time\");\nlet nbVar = env.get(\"nbVar\");\nlet msgArray = new Array();\n\nif(delDup === false){\n    return msg;\n}else{\n    \n    msgArray.push(msg.payload[0]);\n    \n    for(i=1; i < nbVar; i++){\n        if (msg.payload[i].y!==undefined) {\n            msgArray.push(msg.payload[i].y);\n        } else {\n            msgArray.push(\" \");\n        }\n        \n    }\n    \n    msg.payload = msgArray;\n    return msg;\n    \n}\n\n\n","outputs":1,"noerr":0,"x":260,"y":200,"wires":[["f8ba82c4.b6fc1"]]},{"id":"f8ba82c4.b6fc1","type":"split","z":"5442c1fe.bae16","name":"","splt":"\\n","spltType":"str","arraySplt":"1","arraySpltType":"len","stream":false,"addname":"","x":570,"y":200,"wires":[["f131f71e.41cae8"]]},{"id":"4c64fe53.6ea08","type":"file in","z":"34072f28.a29b6","name":"Read file","filename":"","format":"lines","chunk":false,"sendError":false,"encoding":"none","x":280,"y":360,"wires":[["9f1676e1.60b388"]]},{"id":"a30d1a30.036c68","type":"inject","z":"34072f28.a29b6","name":"Start","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":160,"wires":[["d126afb4.cd9c5"]]},{"id":"9f1676e1.60b388","type":"json","z":"34072f28.a29b6","name":"Parse each line","property":"payload","action":"","pretty":false,"x":480,"y":360,"wires":[["fc5b68a9.d4a3b8"]]},{"id":"6605dcb4.d756c4","type":"function","z":"34072f28.a29b6","name":"add a line escape after each payload","func":"let output=\"\";\n\noutput= msg.payload + \"\\n\";\n\nmsg.payload = output ;\n\nreturn msg;","outputs":1,"noerr":0,"x":390,"y":580,"wires":[["51f5a040.55bc5"]]},{"id":"6d6c1729.9217b8","type":"file","z":"34072f28.a29b6","name":"Write csv","filename":"","appendNewline":false,"createDir":false,"overwriteFile":"false","encoding":"none","x":1020,"y":580,"wires":[[]]},{"id":"d126afb4.cd9c5","type":"change","z":"34072f28.a29b6","name":"Set file name","rules":[{"t":"set","p":"filename","pt":"msg","to":"C:\\Users\\[User_Name]\\log\\[File_Name].stcm","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":310,"y":160,"wires":[["4c64fe53.6ea08","907372c9.774d7"]]},{"id":"9f00f046.f52ca","type":"comment","z":"34072f28.a29b6","name":"Enter your filename here","info":"","x":330,"y":120,"wires":[]},{"id":"51f5a040.55bc5","type":"change","z":"34072f28.a29b6","name":"Set csv extension in filename","rules":[{"t":"change","p":"filename","pt":"msg","from":"stcm","fromt":"str","to":"csv","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":780,"y":580,"wires":[["6d6c1729.9217b8"]]},{"id":"a50548d8.3bfa38","type":"file","z":"34072f28.a29b6","name":"Eraze csv","filename":"","appendNewline":true,"createDir":false,"overwriteFile":"true","encoding":"none","x":780,"y":160,"wires":[[]]},{"id":"907372c9.774d7","type":"change","z":"34072f28.a29b6","name":"Format csv header ","rules":[{"t":"change","p":"filename","pt":"msg","from":"stcm","fromt":"str","to":"csv","tot":"str"},{"t":"set","p":"payload","pt":"msg","to":"Timestamp_Data1; Data1; Timestamp_Data2; Data2","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":590,"y":160,"wires":[["a50548d8.3bfa38"]]},{"id":"bc597112.a249b","type":"comment","z":"34072f28.a29b6","name":"Process the stcm file","info":"","x":490,"y":320,"wires":[]},{"id":"14ea3272.6b64ee","type":"comment","z":"34072f28.a29b6","name":"Write the csv file","info":"","x":1020,"y":540,"wires":[]},{"id":"fc5b68a9.d4a3b8","type":"change","z":"34072f28.a29b6","name":"Keep only values","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.variabledata","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":690,"y":360,"wires":[["c3b7abf6.a39f38"]]},{"id":"c4df7459.17d648","type":"comment","z":"34072f28.a29b6","name":"Enter your column names here","info":"","x":610,"y":120,"wires":[]},{"id":"c3b7abf6.a39f38","type":"subflow:5442c1fe.bae16","z":"34072f28.a29b6","name":"Group variables in a .csv file","env":[{"name":"nbVar","value":"2","type":"num"},{"name":"delete_time","value":"true","type":"bool"}],"x":980,"y":360,"wires":[["6605dcb4.d756c4"]]},{"id":"23b9924a.7ee32e","type":"comment","z":"34072f28.a29b6","name":"Enter the number of monitored var & boolean condition","info":"","x":1000,"y":320,"wires":[]}]

Menu > Import > Clipboard and Copy/Paste the .json formatted flow in the area, click on Import. The flow is now imported into the STM32CubeMonitor workspace.

1.2 Configure the flow

Before the first file conversion, the flow must be configured:

• "Set file name" : in the "Set msg.filename to ..." set to [STCM_File_Absolute_Path]. Here is a configuration example:

• "Format CSV Header" : this node is used to define the .csv file column names. Fill the "Set msg.payload to ..." field by putting the .csv column names in the "to" field. The user must choose to display one timestamp for all variables monitored at the same time, or to display each timestamp for each variable. The data are acquired like this:

Time_Data1, Value_Data1, Time_Data2, Value_Data2 ...

Configuration example:

• To display one timestamp for all variables monitored at the same time:

• To display the timestamp of each variable:

Warning

The column names must be set in the same order as acquired data (order given by the variable node of the acquisition flow)

• "Group variables parameters": To configure this node, two parameters are needed:
  • Number of Variables: the number of monitored variables
  • Single Time: a boolean value to define if the user wants to display (or not) the timestamp for each variable (default value set to False) :
    • True: Only one timestamp
    • False: One timestamp for each variable

1.3 Convert the file into a .csv file

When everything is configured, press the square button of the "Start" node to launch the conversion.
To find the .csv file, go in the same folder as the .stcm one. In this folder, a new .csv file (with the same name as the .stcm one) has been created.

1.4 How does the flow work?

The conversion is started on the press of the Start button. The read file node parses each line of the log file and sends it to the "Group variables" subflow. Then the subflow formats the data in a ".csv way" and sends it to the file node. This file node creates a new file: the .csv file corresponding to its .stcm.

How does the "Group variables" subflow work? This subflow associates the values with the same timestamp and then lets the choice to the user to display the duplicated timestamp or not. Ultimately, it formats the data in a ".csv way".

2 Log data directly in a .csv file

This method allows the user to generate a .csv file directly without using an intermediate .stcm file.

2.1 Import the flow

To perform this, import the following flow in the STM32CubeMonitor workspace:

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    \n            for(n = 0; n < nbVar; n++){\n                msg1 = msg.payload[n][j];\n                msgArray.push(msg1);\n            }\n    }\n    msg.payload = msgArray;\n    return msg;\n}","outputs":1,"noerr":0,"x":650,"y":80,"wires":[["b3b24fdd.b01b9"]]},{"id":"b3b24fdd.b01b9","type":"split","z":"7e9c50ed.2ab67","name":"","splt":"\\n","spltType":"str","arraySplt":"${nbVar}","arraySpltType":"len","stream":false,"addname":"","x":870,"y":80,"wires":[["cf754130.7de2a"]]},{"id":"ca91d405.238ea8","type":"function","z":"7e9c50ed.2ab67","name":"Format data","func":"let output=\"\";\n\nif(typeof msg.payload == 'number') {\n    output = msg.payload;\n    \n}else if(typeof msg.payload == 'string'){\n    output = msg.payload;\n}else{\n    output = msg.payload.x + \";\"+ msg.payload.y;\n}\n\nmsg.payload = output ;\n\nreturn msg;","outputs":1,"noerr":0,"x":790,"y":200,"wires":[["802c75f2.9f7898"]]},{"id":"802c75f2.9f7898","type":"join","z":"7e9c50ed.2ab67","name":"Join consecutive 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false){\n    return msg;\n}else{\n    \n    msgArray.push(msg.payload[0]);\n    \n    for(i=1; i < nbVar; i++){\n        \n        msgArray.push(msg.payload[i].y);\n        \n    }\n    \n    msg.payload = msgArray;\n    return msg;\n    \n}\n\n\n","outputs":1,"noerr":0,"x":260,"y":200,"wires":[["91613227.a8eb8"]]},{"id":"91613227.a8eb8","type":"split","z":"7e9c50ed.2ab67","name":"","splt":"\\n","spltType":"str","arraySplt":"1","arraySpltType":"len","stream":false,"addname":"","x":570,"y":200,"wires":[["ca91d405.238ea8"]]},{"id":"91d68244.047e7","type":"subflow","name":"Select .csv variable","info":"","category":"STMicroelectronics","in":[{"x":220,"y":120,"wires":[{"id":"e9aa15c3.2c15f8"}]}],"out":[{"x":1180,"y":120,"wires":[{"id":"d287b70e.45b4c8","port":0}]}],"env":[{"name":"varfilter","type":"str","value":"","ui":{"icon":"font-awesome/fa-cog","label":{"en-US":"Variable 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msg;\n}\n","outputs":1,"noerr":0,"x":660,"y":120,"wires":[["d287b70e.45b4c8"]]},{"id":"b724a6a7.177628","type":"tab","label":"Create .csv log file","disabled":false,"info":""},{"id":"f474eca8.7b351","type":"ui_chartst","z":"b724a6a7.177628","group":"1b8f9f84.b59fb","name":"myChart","order":4,"width":15,"height":9,"chartType":"line","curveType":"linear","duration":"10","ymin":"","ymax":"","x":620,"y":300,"wires":[]},{"id":"af306ec4.f0fad","type":"acquisition out","z":"b724a6a7.177628","name":"myProbe_Out","probeconfig":"3ab5d867.e37ba8","x":680,"y":140,"wires":[]},{"id":"be311bcb.2d3738","type":"acquisition in","z":"b724a6a7.177628","name":"myProbe_In","probeconfig":"3ab5d867.e37ba8","x":230,"y":380,"wires":[["d42b7c5c.e9b9"],[]]},{"id":"672c629e.55c89c","type":"ui_button","z":"b724a6a7.177628","name":"","group":"1b8f9f84.b59fb","order":3,"width":5,"height":1,"passthru":false,"label":"Clear 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Menu > Import > Clipboard and Copy/Paste the .json formatted flow in the area, click on Import. The flow is now imported into the STM32CubeMonitor workspace. The flow attached is a complete flow: you may need to merge it with your existing flow or to configure it for your acquisition (set probes, variables and others).

2.2 Configure the flow

Configure the “Select .csv variables” subflows

For each monitored variable, add a “select .csv variables” subflow connected to the processing node output.

Warning

You must link your subflow inputs in the same order as your processing node output.

To configure each subflow, only one parameter is needed: the name of the variable to filter. One subflow is needed for each variable you want to log. In the “Variable name” field put the exact name of the filtered variable.

Warning

The variable name must be exactly the same as in the processing node (without space before and after). You can copy/paste it from the processing node.

Configure the “Group variables” subflow

To configure this subflow two parameters are needed:

• Number of Variables: the number of monitored variables
• Single Time: a boolean value to define if the user wants to display (or not) the timestamp for each variable (default value set to False):
  • True: Only one timestamp
  • False: One timestamp for each variable

Configure the "File" node

In the “file node”, set the absolute path of the .csv file you want to create.

2.3 Generate the .csv file

The .csv file is updated during the acquisition process.
To find the .csv file, go into the folder defined in the “file node”. In this folder, a new .csv file has been created.

2.4 How does the flow work?

The data sent at the output of the processing node are then sent to the "select .csv variables" subflow (one subflow per monitored variable). This subflow filters each variable and sends it to another subflow: "Group variables". The latter groups, sorts and formats the data to create the .csv file.

2.4.1 “Select .csv variables” subflow

This subflow has several roles:

• Filters each variables by its name
• Formats the header of the .csv file
• Ultimately, sends all the data to the “Group variables” subflow

2.4.2 “Group variables” subflow

This subflow associates the values with the same timestamp and then deletes timestamp duplicates depending on the user's choice. Ultimately,

it formats the data in a ".csv way".