Communication Problem RS232 1

[unclebob]

Hi all!

I have to download data into an electronic temperature controler. Its for a 5 MVA dry-type transformer. I need to program fan, alarm and trip temperatures and to make the controler non-failsafe.

So I installed the software on my Lap-top and tried communicating. It failed.

The Com port is ok. I use com 2.
The settings (baud rate, parity, stop bit...) for the software are the same found in the Hardware Manager.
I'm using WinXP. I have the ''error 380'' when i try to send or receive setting from the controler.

The controler is made by Precimeasure and it is model 2242. There's not much info on their WebSite :

http://www.precimeasure.com

My laptop doesn't have an RS232 port. I had to buy an adaptor USB -> RS232 and install the drivers.

In the Hardware Manager, I can see the adapter at COM 2, so it should work, but it don't.

Anyone ever had that problem?

 

[oldfieldguy]

Sometimes you need to use a null-modem adapter. I'm not familiar with the sort of equipment that you're using, but I know that much of the equipment I deal with uses a regular cable, DTE to DCE, but I ran into the same problem you describe when trying to program a Beckwith LTC controller.

A null-modem adapter cured it, as it lets two DTE's or DCE's communicate properly.

old field guy

 

[MikeHalloran]

Here's a record of someone who did:

http://www.tek-tips.com/viewthread.cfm?qid=1200022

I hate when an error is 'resolved' by reloading everything, but the discussion leading up to that revelation may be informative.



Mike Halloran
Pembroke Pines, FL, USA

 

[lz5pl]

Hi, Unclebob,
Your problem with RS232 communication is not uncommon if you haven't real COM port on your laptop. Using of USB/COM converters is a bit matter of chance. In my case I found (just a good luck) immediately the brand to communicate successfully with Siemens relays, but a colleague found the right one after third attempt. The only good point is that they are not expensive.
My suggestion is to buy PCMCIA card with COM port. After finding that gadget we forgot about communication problems. We use cards with two COM ports from different no-name manufacturers without any problems. Just be careful to buy a card suitable for the slots on your laptop - there are two different standards as far as I know.

------------------------
It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant

 

[slavag]

Best solution, bay laptop with real RS232 port ( Dell, HP).
Regards.
Slava

 

[dpc]

I agree that the USB to Serial widget is the most likely problem. We've also had better luck with the PCMCIA serial adapters.

The root problem is really poorly written software.

 

[danw2]

It's difficult to assist when the vendor offers no information on either the hardware or software

Sometimes it pays to take documentation availabilty into account when purchasing products.

Presumably the software you mention is from the same vendor?

You might try a 'loopback' test with your USB-232 converter using hyperterminal (a communications utility in Windows) and a jumper on the RS-232 terminals , to see if data is going out and coming back in using the converter you have.

See National Instrument's tech note here:

http://zone.ni.com/devzone/cda/tut/p/id/3450

I agree that the quality of USB-232 converters is all over the map.

A popular brand frequently recommended on PLCs forum is Keyspan:

http://www.keyspan.com/products/usa19hs/homepage.spml

Dan

 

[unclebob]

Problem solved.
Just be sure the leads are on the right terminals.