Transfer Limitations
USB Bandwidth
USB bandwidth limitation is lower than an Ethernet port’s. This is one of the reasons why using Dewesoft NET is beneficial given that its systems are always connected via Ethernet.
USB 2.0:
- 35 MB/s in theory, \~ 30 MB/s in practice
- Dewesoft USB limit notice at 26 MB/s
- USB 3.0 does not help upstream
General formula for AI and AO channels:
Number of channels * Sample rate * 4 bytes/sample (/2 if HighSpeed)
- CNT channels: Number of channels * Sample rate * 8 bytes/sample
- CAN channels: Number of CAN ports * baudrate/8
- Slave units (only for clock/trigger sync): Sample rate * 8 bytes/sample
It is very important how the USB port is internally wired in the computer - 30 MB/s per single root hub.
Dewesoft calculator is a tool that calculates USB transfer (MB/s) for various Dewesoft devices. Click here to download.
NET Transfer Limitations
The limitations of NET transfer depend on:
- Ethernet speed in case of large bandwidth
- write speed of hard drive in case of large data storage
- CPU performance in case of advanced math
If all PCs in a NET system are connected together with 1Gb LAN cables, each PC can store approximately 25.600.000 samples per second. That number of samples is be distributed randomly between measurement units.
Example:
If a PC stores 100 MB/s of data, it will take:
- 10s for 1 GB
- 1min 40s for 10 GB
- 16min 40s for 100 GB
- 2h 46min 40s for 1 TB