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nullvalue

Terminal Emulator II - Not communicating

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Hello I have a PEB with an RS232 card, and a WiFi serial adapter (configured for 300 baud) plugged into it with (with a db25/db9 adapter). I start up the Terminal Emulator II cartridge.. accept the default settings basically (even parity, com 1, 300 baud). When I type on the TI keyboard I see the PEB slot flash, but I don't receive anything back from the modem. The screen is completely blank even as I type AT commands which should return some data. Any pointers?

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Yes you need a null modem and you're going to find that te2 only does seven bits which most Wi-Fi modems don't support the only one that I found that does is the guru modem



Sent from my LM-V600 using Tapatalk

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Make sure you are using the TI splitter cable to break the 25-pin connector on the TI into two standard RS-232 ports as well, as the connector on the card is not wired like a standard RS-232 port. It is two ports on a single connector. Once broken out, the 25/9 pin cable you are using should work on either port, as long as it is a null modem cable.

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Thanks everyone.. where would I acquire such a cable, or will I have to splice/build one? I see a breakout diagram that was posted here

Would that work?

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I sell them in my store.. arcadeshopper.com

 

However the ti rs232 port is not a standard rs232.

 

You should pull up the rs232 manual and the wifi modem manual and create your own cable. I sell a rs232 breakout box that can be configured to do this and use your existing cable.

 

Greg

 

https://arcadeshopper.com/wp#!/RS232-Jumper-Box-configured-for-MODEM/p/172104040

 

Sent from my LM-V600 using Tapatalk

 

 

 

 

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Thanks, I'll take a look. What if I wanted to connect up an actual 300 baud modem (with a db25 connector)?  I would still need this special cable?

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Exactly. A modem is a modem there are two types of Rs232 connections DTE and DCE

The TI rs232 is one and a modem is the same. I could read the manual and remind myself which one it is but you can read the manual too. Therefore you need a null modem to communicate due to the fact that the send and receive signals are on the same pins on both sides and the handshaking pins are as well.

If you're curious about what a null modem is exactly you could always Google it

On a PC the serial Port is the other model and a modem plugs in with a straight through cable because the pins are not the same..

Greg

Sent from my LM-V600 using Tapatalk

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Ok so I've verified the adapter that I have does break out the pins from DB9 to DB25 the way the TI is expecting for Port 1. I've updated the source code for my wifi modem to use 7 data bits (source is based on https://github.com/jsalin/esp8266_modem) and verified that worked, yet I still can't get this thing to talk to the TI. One thing that may be a problem is that the RS232 adapter in use only brings out VCC, GND, Rx and Tx to the ESP8266. Are the other lines controlled typically by the MAX232 chip?

 

EDIT: Well maybe I spoke too soon. I just found this diagram which differs from the one I was using. I'll give this a shot.

ti99_rs232_splitter_cables.gif

Edited by nullvalue

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I'm not familiar with that WIFI modem as I have used something different.  Is there a default baud rate the modem is configured?  My modem, had a much higher default baud rate that you had to send it an AT command at that baud rate prior to using it at a different working baud rate.  Simply changing the baud rate on the terminal emulator was not sufficient to use it at a different baud rate.


Beery

 

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Depending and what modem you have it's probably 1200 baud 8n1

You can find that info in the manual for the modem or the firmware if you built your own


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Success! Following the schematics above, I was able to build a cable which is working. My fix to the source code linked above also works.. Basically anywhere there is Serial.begin(xxx); was replaced with Serial.begin(xxx, SERIAL_7E1); - 7 data bit support is built into the Arduino Serial library.

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