My question is pretty straightforward. I've got a big old machine that has an RS-485 connection on the back and I've got a converter from RS-485 to 9 pin serial.
The device I'm connecting to sends out an ACK signal to see if anything is connected. How do I wire up my Arduino (Uno) to the 9 pin serial connector so that I can read the ACK (and in future write back) and display the ACK signal in the Serial Monitor?
I would first check the voltage of the data lines coming from the RS-485 converter. The arduino ports are expecting 0 to 5 volts. Also, look-up the standard for RS-485 to determine what should be on the lines from the RS-485.
Notice, the arduino does NOT directly implement an RS-232 port. Rather, it has a USB port for connecting to a PC. I know that the RS-232 connection does NOT use TTL or 0 to 5V signals, and would question what signal levels are produced by an RS-485.
If the RS-485 does NOT generate 0 to 5 volts, then you will need to get an arduino RS-485 shield.
Finally, in fact, this is what you need to do. I just searched on "RS-485 Arduino" and found multiple hits.
Now, this is the good news, because once you have installed a RS-485 shield then you connect the shield to pins 1&2 on the Arduino and you have a serial connection!!
In most cases you need to wire only RX, TX and Ground signals (RX of Arduino to TX of RS-232 and vice versa). But it really depends on your RS-485 converter, if you need any additional lines. If this converter is half-duplex, may be you will also need to control it with DTR signal. You can use any digital IO on UNO then, and control it in software. Also you need to know the speed of serial port of this old machine, and configure UNO serial port accordingly.
Related
I've been working with a Siemens PLC to send data using RS232. The communication itself is working perfectly, I can monitor it if I connect the PLC to my PC (via a serial comm port).
Now, I wanted to make this communication wireless. I found out about the HC-05 modules and decided to get a few. I set 2 of them up with my arduino (one as master, one as slave, both paired and using the UART 9600,1,0 which is the same that my PLC uses).
I made the following connections:
PC Connection (with a serial comm adapter)
PLC Connection
Let's say I want to send this string:
<SoH>1RZ<CR>
If I check my serial monitor, I get weird stuff. Like:
##NULL©#NUL
The weird thing is that if I just remove the bluetooth modules and connect the PLC's Rx and Tx to the PC's Tx and Rx, respectively, the data is sent flawlessly. So I know that I have everything sorted out on the PLC/PC side.
Has anyone been through this, or does anyone have a suggestion that I can try?
RS232 typically uses ±12V. Negative voltages between -3V and -15V is logic high and positive voltages +3V till +15V is logic low.
Your bluetooth module on the other hand uses TTL logic. With a voltage range of 0-5V.
0-0.8V is low, 2-5V is high.
So
a) you cannot create the necessary voltage levels
b) you risk to destroy your 5V hardware by connecting it to ±12V.
c) you might run into problems as RS232 also has optional mechanisms for flow control. So Rx and Tx might not be enough.
You'll at least need a TTL-> RS232 level shifter for the PLC side and a USB to TTL serial adapter for the PC
Micro and Leonardo have two serial ports, denoted by "Serial" and "Serial1."
I can use Serial1 through the RX and TX pins for my sensor, a TF Mini, and still get output to the Arduino IDE through the Serial connection via USB.
I would like to, instead send that output via Bluetooth, which also requires a serial connection. I have attempted Software Serialization solutions for the sensor, without success.
Is it possible to access both Serial and Serial1 connections through the pins?
The Serial port in the Arduino Leonardo is virtual, so there is no physical way to interact with it, you'll need to do bit banging in other GPIO pins to simulate this connection. By doing this, it will slow down your sketch if you are doing more complicate stuff. And if you add an extra connection via Serial1 port, will be worse.
I've got my sim900 module working with arduino by using their software serial library, however, I want to eliminate arduino from the equation and have serial communication directly to sim900 module.
I'm using putty as my terminal emulator. It's serial is configured to COM1 19200 8 N 1 the same as device manager configuration for this port.
I connect straight from hardware serial on my PCs motherboard into serial-to-ttl interface board which connects to sim900 module. The board has 4 pins - VCC GND TX RX. They're all connected to my sim900 hardware serial as follows: VCC=5V GND=GND TX=TX RX=RX (Yes I know that it's always actually TX=RX and RX=TX, but when I connect it that way my interface board doesn't blink any led to indicate a transfer whereas it does when I connect TX=TX and RX=RX). The switch on the module is set to hardware serial pins as well.
So the only thing that happens when I send AT commands such as AT or ATI and press enter is that puttys cursor comes back to the beginning of command that I typed. No response.
I'm thinking that I'm not doing something that the arduinos software serial port is doing when it sends commands to sim900.
Can anyone help please ? It's literally been days of trying different configurations with no results.
In that time besides getting sim900 working with arduino software serial I verified that the hardware serial port on my motherboard is working correctly and the interface board is working correctly as well.
I have an Arduino 2560 and would like to send serial data to my PC. However, I am currently not using the Arduino Bootloader because I wanted to use a program that I wrote for an Atmega644 before (as far as I understood, one has to use the Arduino language when using the Bootloader?).
Does anyone know if what I am trying to do is possible with reasonable effort?
Connection to PC via 2560's serial0 does not depend on bootloader (if you plan connection when main program is running). You need 16u2 running to bridge 5V serial UART to USB or you can of course use any other option (e.g. MAX232 or so) to convert 5V UART to USB or RS232. But in case of RS232 double check baud rate error because of 16MHz crystal for particular baudrate.
2560 bootloader just implements firmware flash.
I just start a project which is very basic actually. But I need an information. It is about arduino serial communication. Here is the question.
If I connect arduino to computer using TTL to RS232 converter without USB cable then can I still use serial monitor to get some data or what happens ? Assume arduino is programmed before using usb cable, and it is powered externally when usb is not used.
for instance the code just
Serial.println("It is working");
delay(1000);
Thansk a lot.
you will fry it. Standard RS232 use a +-12V level, while arduino use TTL level (0-5V), so you still need a RS232 -> RS232TTL converter. If you use it, then using virtual serial over USB or real hardware serial is exactly the same, except that hardware serial port never appear/disappear when you plug in the arduino (there is not something like plug'n'play in rs232, it is always plugged)