Tic T249 , RS232 and Lora

Hi all,
I have successfully connected and configured with tic control center a T249 and stepper motor through usb interface, all is ok.
Now i want to control the T249 remotely wireless.

to do so, i bought a Lora wireless rtx module with rs232 interface
one Lora module is connected to 5V,GND,RX and TX pin of T249.
On the other side, the second Lora module is connected to my pc, and create a COM14 serial port correctly.
Wireless connection between Lora modules is ok, if I open COM14 with putty and send some ramdom characters both leds that are present on Lora modules blink.
But problem is that i can’t get Tic control center work; when i open it , it says that device is not connected and there is no way to tell it to use COM14.
How can i force tic software to use that serial port?
Or there is another way ?


other investigations I did:
here Lora module pinout based on their doc:
VCC -> 5V in
GND -> ground
RXD -> Serial communication data reception
TXD -> Serial communication data transmission

so, I connect Lora GND to TIC GND, Lora 5V in to TIC 5V out
here Lora module power up and start,
then i connect RXD Lora to TX pin of TIC,
and then when i connect Lora TXD to TIC RX pin the red led of TIC lights up and if i check with usb cable and tic control center it tells me VIN low error.

other “strange” thing is that
with a voltmeter i check between GND and TX and between GNX and RX TIC side we have 5V
between TXD and GND Lora side -5V (negative)
between RXD and GND Lora side zero volt.

Hello, Walter.

It sounds like you connected your Lora device’s RS-232 port directly to the Tic’s TTL serial lines. You should definitely not do that; the Tic cannot handle RS-232 voltages, specifically negative voltages. That kind of connection would likely permanently damage the Tic. There is a warning in the Tic Stepper Motor Controller User’s Guide under the “Setting up serial control” section stating to use an inverter and level shifter like the MAX232 or an RS-232 adapter (like this one) to convert the signals between the Lora device and Tic.

For the Low VIN error you are getting, the Tic T249 expects VIN to be 5.5 V and higher. You can find that information under the “Configuring and testing the stepper motor” section of the Tic Stepper Motor Controller User’s Guide. How did you power the Tic and stepper motor before when your setup was working with the Control Center?

To control the Tic through its TTL serial interface, you would need to use serial commands, not the Tic Control Center. The Tic Control Center uses the Tic’s native USB interface. I highly recommend reading through the “Setting up serial control” section before you continue.

- Amanda

Hi Amanda,
thanks for your reply, but in your documentation is written:
If your serial device operates at 5 V, you can directly connect the device’s TX line to the Tic’s RX line and connect the Tic’s TX line to the device’s RX line.
If your serial device operates at 3.3 V, then you might need additional circuitry to shift the voltage levels.

but my Lora device already work with 5V logic level, not 3.3V.

Also Low VIN error comes up when i connect TX Lora to RX TIC, and VIN is always the same : 12V 20A
when i use UBS or i try RS232.

In your previous post, you said you measured -5 V on the Lora’s TXD line. Like I said, the Tic cannot handle negative voltages, so it is unsurprising that the Tic is malfunctioning. RS-232 voltages are typically well outside the range for a microcontroller I/O line and is different than TTL serial.

- Amanda

Ok i get my mistake… rs232 is NOT ttl serial !

thanks Amanda