I just got an Extech data logging light meter and can't establish a connection. I am using an older laptop running windows 98ME. I got a USP to DB9 (serial) adapter from tigerdirect. I installed everything and changed the adapter port to COM8 (defualt was COM10). The extech sofware only goes up to COM8, hence, me changing the COM port. Anyone else out there know what I am doing wrong? Better yet, how do YOU use this meter in your setup?
Extech Data Logging Light meter question
- Thread starter vio765
- Start date
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Mr Happy
Flashlight Enthusiast
Getting USB to Serial adapters to work with some devices can be a bit of a lottery. I can't help you specifically except to mention that I have tried the Cables Unlimited model USB-2920 serial adapter to connect an XP laptop to the Radio Shack #22-812 multimeter and found it to work well.
Do you have any other serial interface devices to test the USB adapter with?
Also see if you can find an updated Win98 device driver to install.
If you have an "older" laptop, I am surprised it does not already have a serial port built in? Most laptops running Win98 would usually have included one.
Do you have any other serial interface devices to test the USB adapter with?
Also see if you can find an updated Win98 device driver to install.
If you have an "older" laptop, I am surprised it does not already have a serial port built in? Most laptops running Win98 would usually have included one.
csshih
Flashlight Enthusiast
man, lucky you have a data logging light meter.. I can't afford them 
Justin Case
Flashlight Enthusiast
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- Mar 19, 2008
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Are you saying that you have an Extech that has a USB port and you want to connect it to a W95SE laptop that has only a serial port?
I would check the following:
- do you need a straight through or crossover (null) serial adapter
- do you need a driver for the adapter
I would check the following:
- do you need a straight through or crossover (null) serial adapter
- do you need a driver for the adapter
I have concluded that using a 9-pin (DB9) to USB adapter doesn't work. So I ordered a 25-pin (DB25) male to male cable. Here is the setup:
Datalogger>supplied data logger cable with DB9 Female on the end>supplied DB9 Male to DB25 Female coupler>to my ordered DB25 Male cable>DB25 Female port on my PC.
Hopefully this will work, but I won't know until the beginning of next week. IF this doesn't work, my other options are to buy an old laptop with an old DB25 Male port on the back that still has a CD-ROM drive and Windows 98 or XP on Ebay OR look at newer datalogging light meters OR abandon the whole thing.
Datalogger>supplied data logger cable with DB9 Female on the end>supplied DB9 Male to DB25 Female coupler>to my ordered DB25 Male cable>DB25 Female port on my PC.
Hopefully this will work, but I won't know until the beginning of next week. IF this doesn't work, my other options are to buy an old laptop with an old DB25 Male port on the back that still has a CD-ROM drive and Windows 98 or XP on Ebay OR look at newer datalogging light meters OR abandon the whole thing.
Mr Happy
Flashlight Enthusiast
Oh, I didn't catch that. I'm not sure that can be made to work. USB is a bus interface, and one end (usually the computer end) has to be a hub.
USB-to-serial adapters are usually intended to add a serial port interface to computers that only have USB ports. If the Extech meter has a USB interface and the PC does not it would have to act as a USB hub rather than a client device, and I think this is unlikely to be the case.
EDIT: I just saw your last post and now I am confused. You said the datalogger comes with a cable that has a DB9 female on the end. So normally you would plug this directly into the DB9 male serial port on the back of your laptop. If your laptop happens to have a DB25 serial port on the back (beware: this is more likely to be a parallel port) you just need a simple 9-pin to 25-pin serial adapter. You do not apparently need any of the extra cables and adapters you are mentioning, and you do not need a USB adapter.
What is the model number of the Extech meter you have?
If you have a digital camera, perhaps take a picture of the back of your laptop and post it. Also post a picture of the meter and the supplied meter cable.
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EDIT: I just saw your last post and now I am confused. You said the datalogger comes with a cable that has a DB9 female on the end. So normally you would plug this directly into the DB9 male serial port on the back of your laptop. If your laptop happens to have a DB25 serial port on the back (beware: this is more likely to be a parallel port) you just need a simple 9-pin to 25-pin serial adapter. You do not apparently need any of the extra cables and adapters you are mentioning, and you do not need a USB adapter.
My laptop desn't have a male DB9 port, it has a female DB25 and female DB15 port only. plus a few UBS ports. As for the serial vs. parallel: there is a tiny picture of a printer under the port on the back of the laptop. hmmm, know of any common places where i can get that DB9 male to DB25M coupler? lol
My laptop desn't have a male DB9 port, it has a female DB25 and female DB15 port only. plus a few UBS ports. As for the serial vs. parallel: there is a tiny picture of a printer under the port on the back of the laptop. hmmm, know of any common places where i can get that DB9 male to DB25M coupler? lol
Mr Happy
Flashlight Enthusiast
Ah, more info, this is good, but still not quite enough information. The 15-pin female port is the video out for an external monitor. The 25-pin female is a parallel printer port. It is no good for serial communications so don't try to connect to that. A serial port on a computer, if it exists, will always be a male, never a female socket. And unless the computer is 20 years old, it will be a 9-pin socket and not a 25-pin.
Can you give a link or a model number for the Extech meter? Maybe you can plug it directly into your PC with a USB cable. Otherwise, a USB-to-serial adapter like this one should work.
Mr Happy
Flashlight Enthusiast
Ah, that's the information I was looking for. The meter has a serial interface (very common with data logging meters). In that case it should work with a USB-to-serial adapter like this one I linked to above. I have one and it works fine (albeit on XP). I found it in Fry's, if you have one of those nearby.
I got a serial to USB adapter from tigerdirect, but it just wouldn't work. I am now suspicious of serial to USB adapters. But since serial and parallel don't mix, the new cable i ordered isnt going to work no matter what. Is that right? I will look for a new serial to usb adapter and try it.
Mr Happy
Flashlight Enthusiast
Did you buy this one? If so, that's the one I have and it should work. I gave it 10/10.
You might want to try an updated device driver for it. If you wait until I get home later on, I will look up where you can download the latest driver version. (It is based on a standard chip inside and you can download a driver direct from the chip manufacturer.) My only concern is that it might be a bit harder to get plug-in hardware devices working under Win98 than under XP.
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i didnt purchase the you did. I got the one named Ultra. And just to be clear, you also have the same light meter i do? what operating system are you running and what is your setup? if i can replicate what you have (which doesn't seem too difficult), maybe my problems can go away.
Have you checked that this converter is fully compatible with the RS232 standard?
I'm asking because I remember that the USB to RS232 converters are currently a complete mess. Some converters include a DC/DC converter to supply correct RS232 standard voltage levels, some don't and give only +5V as supplied by the USB bus. The standard requires the logic signals to be outside of the -3V, +3V range but many devices that use RS232 port will accept 0V as the logic 1, in direct violation of the standard. There are also more subtle problems - I remember issues with signal timing and flow control settings.
The bottom line is that many devices will work with not standard compliant USB to RS232 converters. You may be quite satisfied with them, until you try to connect something, usually more "industrial grade" equipment, that strictly requires the correct RSR232 behavior on the other end of the cable.
Mr Happy
Flashlight Enthusiast
No, I have the Radio Shack data logging multimeter #22-812 and I am connecting it to a laptop running XP. I know this is not exactly what you have, but I mentioned in particular the USB-to-serial interface that I have because the indications are that it is a good and trustworthy one. Almost everyone who reviews it finds it to work as advertised. This is not true of many other USB-serial adapters on the market.
Mr Happy
Flashlight Enthusiast
I understand that many USB-serial adapters can be problematic and this is why I mentioned that in my post #2 above. However, not every serial interface complies exactly with RS232 or RS423, yet there is a lot of forgiveness in how they work and few problems exist with "real" serial interfaces as found directly installed in computers or on other peripherals.
The problems mainly seem to be with the USB-serial interface devices. All you can do is try to pick one out that gets good reviews and try it. The Cables Unlimited USB-2920 one I have tested seems to be in the "good" category.
Alan B
Flashlight Enthusiast
USB to serial adapters vary. Try more than one type.
I mentioned the problems because the Extech that vio765 bought seems to be somehow demanding - we know that it didn't work with one of the USB to RS232 converters. I thought that maybe you know how the USB-2920 works internally or for example know what are its voltage levels. The voltage isn't obviously everything but it is easy to check and if it is +/-12V, the chances are that the manufacturer at least tried to build something standard-compliant.
On the other hand some stores (e.g. here) sell this Extech with USB to RS232 converters as optional accessories so it could be expected that such converters should work.
Mr Happy
Flashlight Enthusiast
I have not measured the voltages from the USB-2920 as I have not had problems with it and I do not have a break-out box to help examine the signals. However, I did discover the manufacturer of the chip set used inside the device, and I got the impression of them being a solid and reliable chip designer that knows their business. If I can find it again I will post the link.
In fact, this is them: http://www.ftdichip.com/
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My 807026 only works on Com1. Thats with the Extech DB9 Serial to 1/8 Mono plug.
That particular cable can be duplicated with RadioShack parts for ~$10.00, I can give you the pinout if you pickup a computer with a serial connector.
-Michael
That particular cable can be duplicated with RadioShack parts for ~$10.00, I can give you the pinout if you pickup a computer with a serial connector.
-Michael
