Strip-Chart Recorder

Operator Menu Location: Data Logging and Recording

Operator Bitmap:

Functional Description:
The Strip-Chart Recorder logs signal data to non-volatile memory for long-term storage. The operator time-stamps every sample set it records. The time-stamp is based on the underlying hardware's real-time clock and includes the date (MM/DD/YYY) and time (HH:MM:SS.MMM). When the operator's memory buffer fills up, it discards the oldest records in the log to make room for new samples.

The Strip-Chart Recorder has a variable number of inputs---the user defines how many signals are to be recorded. The sampling frequency and total number of samples to store are also properties of the operator.

The operator records data only while enable input E is HIGH. If E is LOW the operator ignores its signal inputs. Reset input R clears all recorded information in the data log.

To retrieve the data set recorded by the operator, select the Query Data Recorder Resources item from the Communications menu in Design Pad or Schema Viewer (while establishing a wired or wireless connection with the hardware). The application will retrieve all data sets stored in the target hardware and identify each set with the name assigned to the operator. Once the data set is selected, the application will retrieve the log file from the hardware and prompt the user to save to disk on the PC. The format of the file is tab-delimited text, permitting import to data analysis and charting programs such as Microsoft Excel.

User-Defined Properties:
Data Set Name. The name used to identify the data set recorded by this operator.

Number of Digital Inputs. The quantity of boolean type input signals to be recorded.

Number of Analog Inputs. The quantity of float type input signals to be recorded.

Record Interval. The time that must elapse between consecutive recorded samples in milliseconds. The default value is 60,000 milliseconds, specifying that signals are to be recorded once every minute.

Number of Samples to Store. The total number of samples to be recorded in the data set. Once all samples are recorded, the oldest samples will be discarded to make room for new samples. The default value is 1,440; with a Record Interval value of one minute (60,000 milliseconds), this setting specifies that the operator is to maintain one day (60*24=1,440) of data.

Display Enable Input. This property determines if input pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Display Reset Input. This property determines if input pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Display Memory Full Output. This property determines if a boolean output pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Display Sample Count Output. This property determines if an analog output pin is visible in the schema diagram. Design Pad issues a warning upon processing the schema when the pin is visible but not connected. The warning message is not issued when the pin is not visible (when this property is not checked).

Comments:
•The amount of non-volatile memory consumed by each sample is

where is the number of analog inputs, is the number of digital inputs, and where  denotes the ceiling operation (meaning round up to the nearest whole number). The elements of the formula suggest that each analog input sample requires 4 bytes, digital input samples are packaged into single 8-bit byte chunks, and the time stamp requires 6 bytes.
•The total amount of non-volatile memory consumed by the operator is

where is the total number of samples per snapshot, and is the sector-size of the non-volatile memory medium (typically bytes for Chameleon modules). The last element of the formula above includes a 3-byte sector stamp used for internal file management purposes. The result of the computation above should be rounded up to the nearest bytes. For example, if , , , and , then

The total memory consumed is obtained by rounding up 23136 to the nearest integer divisible by 512; the result is 23552.

•Multiple data recorders can be included in the same schema / hardware module. The limiting factor is the amount of non-volatile memory (e.g., flash memory) available in the target hardware module.

See Also: Snapshot Recorder