1. Home
  2. Electronics Design
  3. any suggestion to improve RS232 Signal Quality?

any suggestion to improve RS232 Signal Quality?

Dear All,

Could anybody suggest me what are the possible ways to improve the signal quality of 5 ft long RS232 Serial line at Baud Rate 115200?

I posted a question asking on flash programming failures via RS232 Serial Link, a few days ago.

Here are more details on the issue.

The connection link starts from Embedded PC to RS232 to 3V logic level converter, and then from the outputs of logic level converter would go to the UUT (Unit Under Test) mounted on the Test Fixture.

The failure (flash programming via serial link) at baud rate 115200 Bps occurs if I repeatedly touch the the RX connection point on the Level Converter PCBA using a Digital Multimeter.

So I assume that the line is quite sensitive to noise.

Any suggestions?

Regards

Reply to
Myauk
Loading thread data ...

Don't wrap the RS-232 line around the arc welder. I do 115200 over cables much longer than that without trouble. Look at the signals with a scope.

Reply to
MooseFET

DMMs are evil - if your signals have any bandwidth. Check the input capacitance spec, if it even has one. Scope probes (as has been suggested) are much better. If you have a possibility of a lot of EMI, or grounding problems from high-current surges, consider optical isolation in the line.

Reply to
cassiope

Probably a bad ground connection or a bad cable or connector. Make sure both devices are properly grounded.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
--------------------------------------------------------------
Reply to
Nico Coesel

That is ridiculous. It should work unless the EMP from the nuclear bomb or something like that happens.

Check your setup and signals. It could be that the driver is pulling in one direction only.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

formatting link

Reply to
Vladimir Vassilevsky

THank you all for your kind suggestions and comments.

By the way, as I googled on such problems, I found an article by APC which describes about intersystem ground noise.

formatting link
salestools/FLUU-5T3TEU_R0_EN.pdf and
formatting link
T_R1_EN.pdf)

Little Fuse also sells RS232 Data Line Protectors.

formatting link
data/en/Application_Notes/9DataLine.pdf)

I guess installing them in my system will help to improve the signal quality.

Any suggestions?

Regards

er hammer!"

Reply to
Myauk

Put the circuit in a can, and make a proper 9 pin shielded cable with shielded cans on the cable ends. The connector shells get soldered to the drain wire of the cable shield if foil or a bit of the webbing if copper shielded. You could also place ferrite traps on the cable.

You can buy solid pin, solder cup connectors as well to increase connection integrity further still. The common, cheap Chinese, stamped pin stuff likely would have problems at the max spec for the standard.

Reply to
Archimedes' Lever

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.