The miniSMU MS01 supports continuous data streaming for real-time monitoring and recording of voltage and current measurements. This section explains how to set up and use data streaming for your applications.
Understanding Data Streaming
Data streaming allows your miniSMU MS01 to send continuous measurement data to your computer at a specified rate. Unlike individual measurements that require separate commands, streaming provides:
- Continuous data acquisition without command overhead
- Precisely timed measurements at regular intervals
- Efficient capture of transient events
Data Streaming Capabilities
| Feature | Specification | Notes |
|---|---|---|
| Maximum Sample Rate | 1000 samples/second | Single channel operation |
| Measurement Parameters | Voltage & current | Both values reported |
| Timestamp Resolution | 1ms | Each sample includes a timestamp |
Dual Channel Streaming: When streaming data from both channels simultaneously, the total sample rate is shared between them. For example, each channel will stream at approximately 300 samples/second (600Hz total), but not at 600 samples/second (1200Hz total).
Channel Priority: When both channels are streaming, The channel activated first has measurement priority over the latter activated channel. If measurements are scheduled simultaneously, the first-activated channel measures first, which may cause slight timing variations in the second-activated channel's data points.
Enable Data Streaming
To enable data streaming for a specific channel, use the SOURx:DATA:STREAM ON command, where x is the channel number (1 or 2):
SOURx:DATA:STREAM ON
Example:
SOUR1:DATA:STREAM ON
This enables data streaming for channel 1.
To disable data streaming:
SOURx:DATA:STREAM OFF
Example:
SOUR1:DATA:STREAM OFF
This disables data streaming for channel 1.
Set Sample Rate
The sample rate determines how many measurements are taken per second during streaming.
To set the sample rate for a specific channel, use the SOURx:DATA:SRATE command:
SOURx:DATA:SRATE
Example:
SOUR1:DATA:SRATE 500
This sets the sample rate to 500 samples per second for channel 1.
Notes:
- Setting rates above 750 samples/second will default to the maximum of 750
- Lower sample rates generally provide better measurement precision. Oversample Rate is automatically adjusted to accomodate requested sample rate
- WiFi connections may limit the maximum practical sample rate
Data Streaming Formats
Data is sent in batches of multiple measurements with a CSV format with the following structure:
1,1751317508035,-4.990e-01,-3.870e-05,2
1,1751317508127,-4.987e-01,-3.910e-05,2
1,1751317508727,-4.977e-01,-3.911e-05,2
Data Format Fields
| Field | Example | Description |
|---|---|---|
| Channel Number | 1 | The miniSMU channel (1 or 2) |
| UNIX Timestamp | 1751317507935 | Measurement timestamp in milliseconds |
| Voltage | -4.990e-01 | Voltage measurement in volts (-0.499 V) |
| Current | -3.910e-05 | Current measurement in amperes (-39.1 μA) |
| Range | 2 | Current range identifier (debug only) |
Streaming Performance Considerations
USB Streaming
- Provides most reliable high-speed streaming
- Minimal data loss or timing jitter
- Supports full 750 samples/second rate
- Requires physical connection to computer
WiFi Streaming
- Offers wireless convenience
- May experience occasional packet loss
- Consider using 100-300 samples/second for better reliability
- Network congestion can affect performance
- Distance from access point impacts reliability
Computer Performance
- Graph updates may impact performance on slower computers
- Consider reducing visual update rate for smoother operation
- SSD storage provides better performance for high-speed logging
- Close other resource-intensive applications during critical streaming
Example Applications
Battery Discharge Curve
SOUR1:CURR -0.1 # Set 100mA discharge current
SOUR1:VOLT:PROT 2.5 # Set low voltage cutoff at 2.5V
SOUR1:FIMV ENA # Force current mode
SOUR1:DATA:SRATE 10 # 10 samples per second is sufficient
SOUR1:DATA:STREAM ON # Begin streaming
OUTP1 ON # Start the discharge
Solar Cell IV Response Under Varying Light
SOUR1:CURR:PROT 0.05 # Limit to 50mA
SOUR1:FVMI ENA # Voltage source mode
SOUR1:DATA:SRATE 100 # 100 samples per second
SOUR1:DATA:STREAM ON # Begin streaming
OUTP1 ON # Enable output