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Serial communications problems

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Serial communications problems

Postby TheDivvy » Thu Sep 27, 2007 11:28 am

I have just spent a couple of hours trying to resolve a problem setting up an RH-02 device (though this post is likely to apply to all serial devices (not including USB)).

The software reported "RH02 not opened on COM1" whenever it was run.

I contacted Pico by phone a couple of times, they were friendly but not precise enough with replies to questions posed - specifically "what are the required pin connections for the serial cable". Their response was to say "it uses a standard modem cable". There is limited info in their help files regarding the cable configuration as well. javascript:emoticon(':shock:')
Shocked

For the benefit of others who may come across this problem:

1. The cable required is a male to female (most cases 9 pin D type variety)
2. It is a "straight through" cable i.e. connection of one pin number will be the same pin number at the other connector. (In other words NOT a modem cable).
3. Pins 2, 3, 4, 5 and 7 MUST be connected.

An additional useful note is that when the software is running there should be < -7 volts on pin 4, > +7 volts on pin 7, pin 5 is ground.


Hope this is of some help to future users :D :D
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Postby ziko » Thu Sep 27, 2007 2:52 pm

Hi and thank you for your post.

It was myself that you talked to, although I did initially say it is a standard cable I was under the impression that you had the unit from us as we supply the correct cable, a straight through cable as I did inform you later on.

Whoever provided you with the unit provided you with the wrong cable. It is a standard straight through male to female cable. We never did say it is a modem cable.

Kind regards
Ziko

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Postby TheDivvy » Thu Sep 27, 2007 3:09 pm

"It is a standard straight through male to female cable. We never did say it is a modem cable."

The specifics of grammar are important in engineering - what exactly is a "standard" straight through cable?

Unfortunately when it comes to serial comms cables there is any thing but "standard" which is why I suggested Pico should clearly state the configuration of the cable required. (BTW the first person I spoke to did say it was a "standard" modem cable).

Serial comms cables come wired for RS232 or RS422 or RS485 or Modem use or Null Modem, etc then to add to that some cables are fully populated and others only provide the minimum connections (i.e. pins 2, 3 & 5).

Add to that using a correctly wired pin to pin cable BUT provide too many or not enough connections and it won't work (as in the wrong cable that had been incorrectly put with my RH02 which didn't have 4 or 7 connected).

Wouldn't life be simpler if there truly was a "standard" comms cable, unfortunately there never will be.

BTW thanks for the help you did provide, I wasn't trying to knock Pico more clarify the correct naming and identification of the cable required. The logger is now in place and doing its job. :D
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Postby ziko » Thu Sep 27, 2007 3:33 pm

Yes as I said on the post it was me who you spoke to and I did initially say it was a standard cable.

However I am just glad that is working for you.

Kind regards
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