ELM327-compatible adapters - how to choose

[FORScan]

Update 2019-12-11. Article updated as the following:
- Added reference to OBDLink EX

We are asked every day about adapter's choice. The problem is that there is no easy answer, as there is no ideal adapter that would fit best every specific case. In this article we have tried to address most important issues of the choice problem in most compact way.

Note: For professional work we would recommend to consider purchasing J2534 Passthru adapters that support Ford protocols. ELM327 family is recommended for amateur and semi-professional usage. This article reviews only ELM327 familty of adapters. J2534 Passthru devices will be addressed in a separate article.

1. Protocols

Table 1.1 - Ford protocols

OBDII name / Ford name	OBDII jack pins	Bus speed	Bus min. response time	How to detect
SAE J1850 PWM / Ford SCP	2, 10	41600 bps	20...40 ms
ISO9141 / Ford ISO	7	9600 bps	150...250 ms
CAN / Ford HS CAN	6, 14	500 Kbps	0...20 ms
/ Ford MS-CAN	3, 11	500 Kbps	0...20 ms
/ Ford UBP	3	10400 bps	150...250 ms

Table 1.2 - Ford protocols by model generations
P - primary protocol (PCM)
S - auxiliary protocol (not mandatory for FORScan)

Generation	SAE J1850 PWM	ISO 9141	CAN	Ford MS CAN	Ford UBP	Comment
Ford 1996 - 2003	P	S	-	-	-
Mazda 1996 - 2003	-	P	-	-	-	Some models used SAE J1850 PWM as primary
Ford EU, Mazda 2004 - 2009	-	S	P	S	-	Some models used SAE J1850 PWM as primary
Ford NA 2004 - 2009	-	S	P	S	S
Ford, Mazda 2010+	-	-	P	S	-	HS2, HS3 through MS-CAN

Simplest and quite reliable way to find out what protocols are supported in your car is to make a photo of the OBDII jack. Examples:

Focus Mk2 - only HS-CAN and MS-CAN	Mondeo Mk3 after restyling - J1850, ISO9141, HS-CAN, MS-CAN

Table 1.3 - Ford protocols by adapters

Chip	SAE J1850 PWM	ISO 9141	CAN	Ford MS CAN	Ford UBP	Adapter
ELM327 standard	X	X	X	-	-	ELM327, Kiwi 3
ELM327 with HS/MS switch	X	X	X	X	-	ELM327 marked as Ford, Mazda compatible
STN 1100	X	X	X	-	-	OBDLink SX/LX
STN 115x	X	X	X	X	-	OBDLink MX BT
STN 1170	X	X	X	X	-	ELS27 (old versions), Viaken STN1170
STN 2120	X	X	X	X	-	ELS27 (new version)
STN 2255	X	X	X	X	-	OBDLink MX+
STN 2230	X	X	X	X	-	OBDLink EX

2. Performance

Two parameters are mainly important for performance:
Min. interface respone time (minimal response time or ping) - minimal possible time from the moment request to adapter is sent to the moment the response from adapter is received
Max.interface baud rate - max possible data transfer baud rate between computer and adapter

These parameters directly affect connection time, parameter (PIDs) reading frequence, overall programming time

Table 2.1 - Adapters' performance

Adapter	Chip	Interface	Min.interface response time	Max.interface baud rate	Comment
ELM327 OHP HS/MS WiFi	ELM327 (clone)	WiFi	30-40 ms	38400 bps	Unknown manufacturer - "good clone". Recommended only for iOS
Kiwi 3	ELM327 compatible	Bluetooth Low Energy	40 ms	-	Can be used only with FORScan Lite for iOS
ELM327 HS/MS USB	ELM327 (original)	USB	0..2 ms	500 Kbps
OBDLink EX	STN2230	USB	0..2 ms	2Mbps	Recommended for FORScan for Windows
OBDLink SX	STN1100	USB	0..2 ms	2Mbps
OBDLink LX	STN1100	Bluetooth	-	-
OBDLink MX+	STN2255	Bluetooth	6..20 ms	-	Recommended for FORScan Lite for iOS, Android
OBDLink MX BT	STN115x	Bluetooth	8..20 ms	115200 bps
OBDLink MX WiFi	STN115x	WiFi	-	115200 bps	WiFi interface works unstable - it freezes and times out. Strongly not recommended!
ELS27 v3	STN2120	USB, Bluetooth	0..2 ms USB, 20 ms BT	8 Mpbs USB
Viaken STN1170 USB	STN1170	USB	0..2 ms	2 Mbps	Last versions of this adpater have buggy firmware 4.3.x. Recommended to downgrade to stable 4.1.1 or upgrade to stable 4.5.1
Viaken STN1170 BT	STN1170	Bluetooth	20..30 ms	38400 bps	Uses cheap BT chip so may freeze on some cars. Not recommended

Overall system performance can be easily estimated by adapter's performance and bus parameters as the following:

Overal min.response time = Min. adapter response time + Min.bus response time
Overal baud rate = MIN ( Adapter max. baud rate / 2, Bus baud rate)

Examples:

Example 1: Ford Mondeo Mk3 PCM, bus J1850. Adapter ELM327 OHP HS/MS WiFi. According to the table 1.1, let's assume min. bus response time is 20 ms, bus baud rate is 41600 bps. According to the table 2.1 adapter's min response time is 40 ms, baud rate is 38400 bps.

Overal min.response time = 40 ms + 20 ms = 60 ms
Overal baud rate = MIN ( 38400 / 2, 41600) = MIN ( 19200, 41600) = 19200 bps.

Note: we divide interface baud rate by two because ELM327 family adapters exchange data in text format. So every machine byte is represented in 2 transferred bytes.

As we can see, the adapter significantly limits the overal system peformance in this example (in case of cars with CAN bus, like Mondeo Mk4 or Mk5, the test results would be much worse). Is that bad? Well, it depends on your goals. If reading DTC and some PIDs is the only objective you have, it is not too important. But if you plan to read PIDs in real-time (or as much close to it as possible) or perform programming (actual for CAN bus), then this adapter is a bad choice.

Example 2: Mazda 323 2001, bus ISO. Same adapter.

Overal min.response time = 40 ms + 250 ms = 290 ms
Overal baud rate = MIN ( 38400 / 2, 9600) = MIN ( 19200, 9600) = 9600 Kbps.

In this case the adapter is OK, because the bus itself is very slow. Reponse time is less than 20% higher than maximum possible for this car, and transfer speed is also limited by the bus.

Example 3: Ford Fusion 2015, bus CAN. Adapter ELS27 v3 USB. Let's assume CAN bus response time is 0 ms, and adapter has 2 ms of response time and 2 Mpbs baud rate.

Overal min.response time = 2 ms + 0 ms = 2 ms
Overal baud rate = MIN ( 2000000 / 2, 500000) = MIN ( 1000000, 500000) = 500 Kbps.

So in this case the response time is minimal, and baud rate is limtied by the CAN bus one.

3. Reliability

Two things are important for reliability:

- quality of the adapter. Not original adapters in general case have lower quality than original ones. We will create a dedicated article about so-called "clone problem".

- type of interface. The fact is that wireless interfaces used in ELM327 family of adapters are much less reliable than USB interface. And this problem is actual not only for "clones", but also for "original" adapters (OBDLink MX WiFi and Viaken VScan Bluetooth are most obvious examples).

So in general case we recommend to use USB for Windows version of FORScan, where it is possible. BT and WiFi devices are only recommended for mobile platforms (iOS and Android).

Also, important note about adapters with mechanical HS/MS switch: in addition to the fact it is not very convenient to switch it manually, it may be not possible to perform some operations with this type of adapter. If some operation requires a simultaneous access to both HS and MS (so FORScan needs to access some module(s) on HS CAN bus and, at the same time, other modules on MS-CAN bus), it cannot be normally executed using adapters with mechanical switch. Example: reading parameters (PIDs) in virtual module All, Module initialization subfunction in service functions "Remote keyless entry and Start".

4. Recommendations

Table 4.1 - recommendations on adapters
NO - not recommended for this platform
D - recommended for diagnostic: read PID, read/reset DTC, simple service functions
C - recommended for configuration: write configuration parameters to modules, complex service functions
P - recommended for programming: complex configuration, firmware update (only for CAN )

Adapter	FORScan for Windows	FORScan Lite for iOS	FORScan Lite for Android
OBDLink EX	D, C, P	NO	NO
OBDLink SX	D, C, P*	NO	NO
OBDLink LX	D (if MS-CAN is not required)	NO	D (if MS-CAN is not required)
OBDLink MX+	D, C	D	D
OBDLink MX BT	D, C	NO	D
OBDLink MX WiFi	NO	NO	NO
ELS27 v3	D, C, P	NO	D
Viaken STN1170 USB	D, C, P	NO	NO
Viaken STN1170 BT	NO	NO	NO

* - can be modified for MS-CAN support as described here.

5. Links to original adapters

All of these adapters were tested by us.

5.1. OBDLink product line: https://www.obdlink.com/

5.2 ELS27: http://els27.ru

5.3. Viaken: https://viaken.pl/pl/polski-elm327-v3-f ... -2014.html

Note: actually, all what we write about Viaken adapter is related to older version (v1 or v2, in black case). We had no chance to test their v3 version yet.

[dickiefrank]

I'm getting a reading on the forscan when I try to link it to the truck...says "bad clone"...my connector does not have the toggle switch...am I to conclude that I need the one WITH that toggle switch?

[Vladsky]

I'm getting a reading on the forscan when I try to link it to the truck...says "bad clone"...my connector does not have the toggle switch...am I to conclude that I need the one WITH that toggle switch?

The proper adapter you need is already specified above.

Suggest you start reading, Dickie

Vlad

[nixoid]

I'm getting a reading on the forscan when I try to link it to the truck...says "bad clone"...my connector does not have the toggle switch...am I to conclude that I need the one WITH that toggle switch?

The proper adapter you need is already specified above.

Suggest you start reading, Dickie

Vlad

I haven't looked at too many threads yet but every post I've seen from you has the voice of a troll. Instead of just telling people to read like they're stupid or lazy, try helping out. Not everyone can understand technical info as well as you.

[Scott2373]

Thank you for this excellent info, from this noob! Hopefully I can understand all of this, because there are several changes I'd like to make to the factory settings! Thanks again!

[Johnny641]

I will choose this adapter for my F-150 xlt 2015 3.5 EB, i guess that will be fully compatible with Forscan and my truck?
https://www.amazon.com/VINT-TT55502-ELM ... B01N18TOFB

Tell me if i'm wrong

Johnny641

[ryanynh]

I will choose this adapter for my F-150 xlt 2015 3.5 EB, i guess that will be fully compatible with Forscan and my truck?
https://www.amazon.com/VINT-TT55502-ELM ... B01N18TOFB

Tell me if i'm wrong

Johnny641

I have that exact adapter and have used it on my 14 Fusion to make some mods as well as my 15 F-150 & the kids’ 07 Fusion. Works great. Only thing I dislike is the setup instructions weren’t fantastic and I forget which side of the switch is the MS Can and HS Can.

[mquick5]

I ordered same one today. Hopefully I can figure out how to get the right forscan so I can make program changes.

[ryanynh]

I ordered same one today. Hopefully I can figure out how to get the right forscan so I can make program changes.

I Replied to your PM about the driver download. Depending what you want to do, there is a lot of info on the various forums on the different mods. In a few cases, I was able to get a list of mods and the "code" in an excel spreadsheet so I knew exactly what I wanted to do (such as setting Bambi mode and changing the heated seat & wheel temps).

[mquick5]

I ordered same one today. Hopefully I can figure out how to get the right forscan so I can make program changes.

I Replied to your PM about the driver download. Depending what you want to do, there is a lot of info on the various forums on the different mods. In a few cases, I was able to get a list of mods and the "code" in an excel spreadsheet so I knew exactly what I wanted to do (such as setting Bambi mode and changing the heated seat & wheel temps).

Ty, I have a 2017 Expedition xlt el 4x4. No heated seats. I do like the bambi mode idea. Also I want to enable the fogs to drl, & drive in movie mode on the stereo, as well as the lane change # of flashes. Really was hoping for tps monitor on dash, & maybe boost gauge but no luck with those so far.