Timeline for Basic test for a RS232 serial terminal
Current License: CC BY-SA 4.0
15 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 19, 2018 at 8:40 | comment | added | user6580 | Replaced a 1489 chip - functional terminal! Thanks! | |
| Sep 10, 2018 at 3:34 | comment | added | user6580 | @alephzero Put a multimeter on the port - terminal does transmit since the voltage reading heads toward zero when a key is held down, and the amount it moves depends on the transmission speed. So this terminal has a bad input. Definitely broken. | |
| Sep 9, 2018 at 0:21 | vote | accept | CommunityBot | ||
| Sep 6, 2018 at 22:59 | comment | added | user6580 | Haven't probed with the DMM yet. No scope. I did cat to /dev/ttyUSB0, nothing. Also hooked up the full loopback - I'm pretty sure it's dead. | |
| Sep 6, 2018 at 12:44 | comment | added | Michael Kohne | Also, when you had the terminal hooked to the pi did you try transmitting from the pi, or from the terminal, or both? | |
| Sep 6, 2018 at 12:41 | comment | added | Michael Kohne | @AdamEberbach - do you have a DMM or an Oscilliscope? If you just have a DMM probe the unconnected tx line - even when idle it should be well outside the -3 to 3 range. If you have an oscilliscope, probe the unconnected tx while sending and see if it's moving. | |
| Sep 6, 2018 at 10:59 | answer | added | John Burger | timeline score: 3 | |
| Sep 6, 2018 at 6:57 | answer | added | Jules | timeline score: 0 | |
| Sep 6, 2018 at 5:55 | comment | added | user6580 | @dirkt USB is out of the equation for now - trying to get characters echoed back to the terminal via a simple loopback. If I get past that hurdle will try USB to a pi again. | |
| Sep 6, 2018 at 5:42 | comment | added | dirkt | Another basic test is to measure voltages and see how well they are in the RS232 range. Some USB dongles are very close to the 3V "undefined" level, which can cause trouble with vintage equipment. | |
| Sep 6, 2018 at 3:31 | comment | added | manassehkatz-Moving 2 Codidact | I was going to suggest voltage levels on the USB-RS232 converter, but if even a loopback doesn't work then that's not it. You need one of these I probably have one around here somewhere...used to use them quite a bit a "few" years ago. | |
| Sep 6, 2018 at 1:57 | comment | added | user6580 | good thoughts - I will wire the hardware control loopback and see what I get. This is when you kick yourself for ever throwing anything out as I used to have a breakout box and all that gear. | |
| Sep 6, 2018 at 0:29 | comment | added | alephzero | I would bridge pins to simulate hardware flow control as well, just in case you haven't switched it off! See ni.com/tutorial/3450/en for the DB9 and DB25 pin connections. Also, can you transmit from the raspberry pi to the terminal? You didn't mention trying that in your post. It all else fails, even a cheap multimeter should "flick" the pointer if you are actually transmitting data. A breakout box is a better diagnostic tool - you can get "cheap and cheerful" ones ($25) from Amazon, Ebay, etc. | |
| Sep 6, 2018 at 0:20 | review | First posts | |||
| Sep 6, 2018 at 8:29 | |||||
| Sep 6, 2018 at 0:16 | history | asked | user6580 | CC BY-SA 4.0 |