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TDS2002 - RS232 Levels?

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Chat Zone » Archive through 23 February, 2015 » TDS2002 - RS232 Levels? « Previous Next »

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741
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Username: 741

Post Number: 626
Registered: 08-2005


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Posted on Friday, 06 February, 2015 - 10:13 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

After downloading a user manual, I can't be certain of the RS232 levels. Where are they documented?

My PC seems to use levels like -12V: Perfectly 'legal' -25..+25V level of course.

I'd guess Tek would be happy with that but I'd like to be sure.

I could try probing the scope's RS232 port, seeing what they are when I hit Print I guess.
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pebe
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Post Number: 165
Registered: 05-2005

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Posted on Friday, 06 February, 2015 - 11:41 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi,
Here are the specified RS232 signal levels taken from ‘Data Transmission’ by Tugal & Tugal. I hope you find them useful.

“The interface is designed for short distance working up to 15m, and at data rates up to 20Kbps.

The unterminated output is a bipolar voltage between the levels of +5V to +25V for a logic ‘0’, and between –5V to –25V for a logic ‘1’.

The terminating load should be between 3000oms and 7000ohms. The voltage across the terminating resistor should not be less than 5V nor more tan 15V.

The effective shunt capacitance across the load resistance should not exceed 2500pF”.
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741
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Post Number: 627
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Posted on Monday, 09 February, 2015 - 09:34 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Thanks Pebe.

I was just wanting to be sure I did not damage the ocilloscope (it's borrowed!). I measured the scope's own RS232 output on the scope itself, and levels seem to be "well over 5V" --> scope should be safe (but not an FTDI232 !).

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