USB adapters performance optimization
Posted: Tue Nov 10, 2015 11:38 am
Update February 2023 : The original article was created in 2015 and much outdated. Please do not spend your time trying to make the cheap adapters work. Instead of, please use recommended adapters. Please find more information here:
What adapter should I purchase for FORScan for Windows?
Why should I use more expensive "recommended" adapter instead of regular ELM327?
What are possible problems if I use "regular" ELM327 instead of "recommended" adapter?
Main advantage of USB adapters against Bluetooth and WiFi ones is performance. But sometimes some optimization is necessary to reach the maximum of possible performance. Below we describe some tricks on how to improve USB adapter speed in FORScan.
FORScan shows some adapter parameters in the Vehicle section:
Minimum response time is most critical, as it in fact means adapter delay (time added to every request and response). In this case, it is not so bad, but this adapter may work better. Let's try to fix:
1. FTDI UBS 2 RS232 chips by default have odd 16ms delay reading data from buffer. Our luck is that It can be easilty reduced:
Call Device Manager, find your USB port. (1) Call Properties; (2) Call advanced (3) Change Latency Timer from 16 to 2 or 1 ms.
PC reboot is recommended after this procedure.
This trick works only for FTDI chips. Prolific, Silicon Labs and others have no this latency timer problem.
2. If we check adapter performance now, we will see that minimal response time reduced from 16 to 10 ms:
Well, it's better but still slow. Another improvement deal is to set the Auto-increase option is FORScan settings:
Let's check it and re-connect:
We see great improvement now, FORScan has increased interface speed from 38,4 to 500 Kbps and minimal response time dropped from 10 to 2 ms. This is best reachable delay for china ELM327 USB adapters.
This way is applicable for all USB adapters. You may ask why this nice option is not enabled by default? Answer is simple: initially this option was enabled by default, but it freezes some china adapters, so we have disabled it.
What adapter should I purchase for FORScan for Windows?
Why should I use more expensive "recommended" adapter instead of regular ELM327?
What are possible problems if I use "regular" ELM327 instead of "recommended" adapter?
Main advantage of USB adapters against Bluetooth and WiFi ones is performance. But sometimes some optimization is necessary to reach the maximum of possible performance. Below we describe some tricks on how to improve USB adapter speed in FORScan.
FORScan shows some adapter parameters in the Vehicle section:
- start_en.png (66.21 KiB) Viewed 183146 times
Minimum response time is most critical, as it in fact means adapter delay (time added to every request and response). In this case, it is not so bad, but this adapter may work better. Let's try to fix:
1. FTDI UBS 2 RS232 chips by default have odd 16ms delay reading data from buffer. Our luck is that It can be easilty reduced:
- device_manager_en.png (134.65 KiB) Viewed 183146 times
Call Device Manager, find your USB port. (1) Call Properties; (2) Call advanced (3) Change Latency Timer from 16 to 2 or 1 ms.
PC reboot is recommended after this procedure.
This trick works only for FTDI chips. Prolific, Silicon Labs and others have no this latency timer problem.
2. If we check adapter performance now, we will see that minimal response time reduced from 16 to 10 ms:
- after_ftdi_en.png (57.24 KiB) Viewed 183146 times
Well, it's better but still slow. Another improvement deal is to set the Auto-increase option is FORScan settings:
- start_settings_en.png (66.71 KiB) Viewed 183146 times
Let's check it and re-connect:
- end_en.png (48.25 KiB) Viewed 183146 times
We see great improvement now, FORScan has increased interface speed from 38,4 to 500 Kbps and minimal response time dropped from 10 to 2 ms. This is best reachable delay for china ELM327 USB adapters.
This way is applicable for all USB adapters. You may ask why this nice option is not enabled by default? Answer is simple: initially this option was enabled by default, but it freezes some china adapters, so we have disabled it.