I am using the pymodbus interactive console to interact with a serial device. The device is powered over the communication port itself, namely using the DTR and RTS pins. Thus, they both need to be set high.
The device is correctly powered when using client.connect, however it turns off whenever I try to read any register, probably because neither DTR nor RTS are kept high during the requests.
Is there any way to keep these two pins high using the interactive console? I only saw examples using a script rather than on the REPL.
So far, I am doing:
pymodbus.console serial --method rtu --port /dev/ttyUSB0/ --stopbits 2
client connect --> returns True. Device power LED is on.
client get_serial_settings -->
"baudrate": 19200,
"port": "/dev/ttyUSB0",
"parity": "N",
"stopbits": 2.0,
"bytesize": 8,
"read timeout": 1.0,
"t1.5": 0.000859375,
"t3.5": 0.002005
client read_holding_registers address=49 count=1
--> Error, no response received, Device power LED goes down
Related
I am writing some code for my arduino nano and I am using an HC-05 module for wireless transfer of data. I am sending my data as such. This is from the serial monitor, using a usb and regular print statements. I want to be able to recieve this data, and the store it in a csv (I know how to store incoming data). I need help recieveing my data.
22:17:46.765 -> =============================================================
22:17:47.770 -> Sleep timer:242
22:17:47.770 -> Light Sleep: 0 Deep Sleep: 0
22:17:47.805 -> Total Light Sleep: 0 Total Deep Sleep: 0
22:17:47.838 -> Total Sleep: 0
22:17:47.871 -> =============================================================
For some reason, when I connect my HC-05 to my windows desktop via bluetooth, and open a serial monitor in com ports 3 or 4, I get no read out.
My ports
I have it set up as so.
My wireless intialization
Then, I use
MySerial.print()
, to send data, yet I get no output, same thing occurs if I use
Serial.print()
.
I tried getting a new HC-05 module, Switched out all the hardware, tried different prints including Serial and MySerial. I though i could get an output.
Python code I tried to use python to extract the data, yet I get no output. I am not sure what to do here.
Not enough information, but I'll answer biased on the experience I've had with these modules.
Here are instructions for changing or verifying the baud rate on the module:
https://www.instructables.com/Change-the-Baud-Rate-of-HC-05-Bluetooth-Module-Usi/
For my module, I could just send AT commands by default without putting it into AT mode. Send 'AT' to the module and it should respond with "OK".
It helps a ton if you have an ftdi cable for troubleshooting. Connect the ftdi to the HC-05, verify the baud rate and that the HC-05 is responding, open a serial monitor for the bluetooth on the pc and one for the ftdi cable. Try sending data back and forth. Also, be 100% sure you're using the correct com port for your bluetooth by unpairing and repairing and see which com port shows up.
It actually is possible to use the HC-05 for programming the Arduino as well if you set the baud rate to 115200 and figure out a way to hit reset on the Arduino as soon as the bluetooth connects(status/state goes solid). I used an ATTiny for that, but you could just use a pin on the nano connected to reset and another pin to monitor the "state" pin which is connected to the led on the HC-05. That way you can have wireless data and wireless programming if you wanted that.
I am trying to connect a WiFi module (ESP8266) to a "funduino" development board (Arduino Nano) but I have no success. Since I tried so much schematics I've found on the internet about the connection between them two, I kindly ask here if is anyone who succeed in "pairing" this two devices.
I am asking for the schematic and a functional source code.
Regards
The ESP-01 by default comes with nonOS SDK bootloader that communicated via AT commands, you can find the complete command set from Expressif here. This is designed for an MCU (like Arduino Nano) to use it purely as an WiFi module rather than using it as a stand-alone MCU (for which it will require NodeMCU SDK).
If you ever upload an Arduino sketch up to the ESP-01, it will erase the AT Command firmware.
Assuming your ESP-01 is still having the AT Command firmware. What #Ben provided is a sketch that allows you to type AT commands via the Serial Monitor to internact with the ESP-01, it is manual, and good for testing if ESP-01 is working (you type AT and press return on Serial Monitor, the ESP-01 will ack with Ok) but not practical as a real application. The minimum commands required to established an WiFi connection with ESP-01 is listed below.
AT+CIPMUX=1 - Enable single (0) or multiple connection (1) to the web server.
Multiple connection is a good option if you are repeatedly sending
out or reading data from the Internet.
AT+CWMODE=3 - Set WiFi mode: 1 is station mode (ESP8266 is client), 2 is AP mode
(ESP8266 acts like a WiFi router where your phone or PC can connect),
3 is AP+station mode (make the ESP8266 do both)
AT+CWJAP=“<your-ssid>”,”<your-pw>” - Connect to your WiFi. Provide your SSID name
and password inside the double qoutes.
AT+CIFSR - This returns the IP address of the module, indicating that it has
successfully connected to your WiFi router.
Once the WiFi connection is established, you can further communicate with the ESP-01 via the connection, like accessing a website for example:
AT+CIPSTART=0,"TCP", "www.example.com","80” - Start TCP or UDP connection. The
0 is the id of the connection.
AT+CIPSEND=0,16 - Command to tell the module data is ready to be sent. 0 is the
connection id, and 16 is the length of the data to be sent.
After this command, the ESP8266 will reply with the “>”
character to tell us that it will be waiting for the data to be
sent. If successful, the module will reply with “SEND OK”
GET / HTTP/1.1 - Send the http header, and other data, etc...
You can write your own sketch to automate those AT commands for interacting with with ESP-01 once you understand the AT commands required for establish a WiFi connection.
Here are two resources that I personally found extremely useful for doing more than connecting to WiFi.
STM32-ESP-01 Web Server - although this is for interfacing with STM32, the main difference is the pin assignment, so you should be able to port to Arduino easily.
MQTT via ESP-01
As for hardware interface, please noted that what #Ben provided is correct in principle, but you need to be aware that the ESP-01(ESP8266 to be precise) is a 3V3 MCU, so the connection is depended on what kind of host board you are using. If you are using Arduino Uno/Nano, both are having a 5V MCU, you will need a voltage divider (two resistors to drop the voltage to 3v3 before connecting to ESP-01) or a level shifter chip at least for the ESP-01 Rx pin to avoid the potential damage to the ESP-01.
When I send any commands to the HM10 BLE Bluetooth module, it sends the commands through bluetooth instead of the HM10 module processing the command. For example, I expected to send AT and have the module respond with "OK", but it sends the text "AT" through the bluetooth connection. I have tried sending the command with no bluetooth connection and the same thing happens. I have also tried sending the command via bluetooth instead of the serial connected to the device and I get the same thing.
When HM10 is connected to remote ble device it is in transparent mode. To put it into AT mode you need break connection or not establish it at all.
For breaking connection use reset/break pins. Reset is 12 pin and Break seems to be 23 pin.
It has sense to look IMME parameter of the module (page 32 of datasheet).
IMME Query/Set Module work type
1: When module is powered on, only respond the AT Command, don’t do
anything. Until AT + START, AT+CON, AT+CONNL commands is received.
0: When power on, module will start work immediately Default: 0
Also be carefull with strings endings, usually string doesn't need to be terminated with any symbol at all: AT, but some H11 need the string to end with CRLF: AT\r\n
Maybe (Maybe) your problem because of using clone module, try this solution with upload genuine firmware to your hm-10.
How to flash genuine HM-10 firmware on CC2541
I had problem close from your problem but for me no matter what I send I don't receive anything even to connected device, but after I upload that firmware, and change Module work mode to 1 (AT+MODE1) become able to send command even from connected device.
How can i tell if the unit connected to serial port is powered on?
Does serial communication have any means of acknowledging that a command has been received that i can check for?
or is it entirely dependent on whatevers plugged into the serial port?
Most RS232 devices (such as modems) will raise the DSR (data set ready) line when they are powered on and ready to work. You can query the status of this line in software.
In a similar fashion, computers generally raise DTR (data terminal ready) to tell the modem (or whatever device) that they are ready. You can control this line from software.
Acknowledgement is not specified by RS232 and varies from one device to another, but many devices do indeed use hardware handshaking to indicate willingness to receive data. Specifically, they will raise CTS (clear to send) when they are ready. If the device is powered on, but can temporarily not receive data, it will leave DSR high, but will clear CTS.
I have an Arduino sending and receiving instructions with a Python script via a serial port.
The Arduino takes a button state and when it is pushed, it will send a message via the serial port to a Python script and await a response. (via Serial.available()). It works well enough.
However, if the Python script has crashed for whatever reason (ideally it will run in the background, so it can't be easily checked), the Arduino will wait forever and will be unavailable even on a script restart.
Is there a way for my Arduino to check if there is something listening on the serial port? (and alert me with flashing lights, etc. if not) or is this not how serial works? Worst case I guess I could use a timeout, although that is not ideal.
You have a limited ability to detect if there is something listening on the other side by using the DSR/DTR pins.
When you open the serial port on the machine your scripts runs on, it should raise its DTR pin (or you should be able to convince it to do so: the documentation of the library you use to drive the COM port should tell you how).
Then, on your Arduino, you can check its DSR pin (assuming null-modem wiring with handshaking, where the PC DTR pin is wired to DSR+CD on the Arduino) at regular intervals, and handle the 'nobody connected' scenario in any way you see fit.
One problem with this approach is that your PC script may not close the serial port when it crashes/stops responding, leaving the DTR pin enabled as if everything is still OK. Also, your script may simply miss the message from the Arduino due to errors on the serial line.
For that reason, you should always implement a timeout in your receive routines: even if there is a party listening at the other end, there is no guarantee it has received your message (or that its response will reach you intact).
Re-sending the message at least once (assuming DSR is raised) if a timeout occurs makes your protocol more reliable.
The Arduino doesn't use the DSR line or any other handshaking line, so you can't do what you suggest.
I agree with mdb that timeouts are necessary, but would also add that you might want to implement simple challenge/response system that periodically checks if anyone is listening. (I like ircd's Ping-Pong analogy).