CSV format reference

This page describes the format of .csv files written and read by ModbusScope.

File structure

Time (ms);Signal 1;Signal 2;Signal 3
0;100;200;300
250;101;201;301
500;102;202;302

Row 1: column headers. The first column is always the timestamp header; subsequent columns are signal names.
Rows 2+: one data row per poll cycle.

Column layout

Column	Content	Type
1	Timestamp	Integer (ms from session start) or absolute date-time when absolute timestamps are enabled
2..N	Signal values	Numeric, one column per signal in the order they appear in Signals

Data quality columns

Files written by ModbusScope contain a //Quality;1 header line, written with the file’s field separator (//Quality,1 in a comma-separated file). It means every signal column is directly followed by a quality column for that signal. Quality column labels end with (quality):

//Quality;1
Time (ms);Temp;Temp (quality);Press;Press (quality)
0;21.5;0;1.02;0
1000;21.6;129;1.02;0
2000;21.6;2;1.03;0

The quality code is state + flags:

Code	Meaning
0	Good
1	Degraded
2	Invalid (value is the last valid value, 0 if there was none yet)
3	No value (value is the last valid value, 0 if there was none yet)
+16	Substituted
+32	Blocked
+64	Overflow
+128	Old data

For example, 129 is Degraded with Old data. On import, the value of every sample is read as written, an empty quality cell reads as Good, unknown flag bits are ignored and an unknown state reads as Invalid. Files without the //Quality line load with every sample marked Good.

Separators (export)

ModbusScope uses system locale settings when writing. Typical combinations:

Locale	Field separator	Decimal separator
English	`,`	`.`
Belgian / French / German	`;`	`,`

Separators (import)

ModbusScope attempts to detect the separators automatically when opening a file. If detection fails, set them manually in the import dialog. See Open a CSV data file.

Setting	Meaning
Field separator	Character between columns
Decimal separator	Character between integer and fractional part
Thousand separator	Grouping character (may be absent)

Timestamp units (import)

Setting	Behavior
Milliseconds (default)	Timestamp column read as-is
Seconds	Timestamp values multiplied by 1000 on load