I am using micropython in esp32 with umodbus lib for reading the holding register (2 registers). after reading i am looking for the option of how to get the value. the temperature value is set in 2 registers say 30005 and 30006, I got the value, but looking for how to decode the value and get a floating value.
Related
I have a Spektrum Radio transmitter, along with its receiver. What I am currently trying to do is by using microPython and a Raspberry Pi Pico, I want to read the data coming into the receiver, and convert that into servo commands. All I know is that the protocol used by the transmitter/receiver is DSMX. How can I go about doing this? I only need to receive, I don't need to transfer any data back from the Raspberry Pi Pico.
I'm using Thonny, and all I've done is try to use the UART module and ustruct module and create a variable using that
uart = UART(1, baudrate = 115200)
data = uart.read()
header,id,data,error_checking,trailer = ustruct.unpack('>BBHHB',data)
When trying to run this, I get thrown the error
TypeError: object with buffer protocol required
I didn't expect anything, as I don't really know what I'm doing.
Any help would be really appreciated.
You're getting that TypeError exception because your call to uart.read() is returning None (meaning that there was no data available on the serial port). I don't know anything about the DSMX protocol, but to avoid that error in your code you probably want something like:
format = 'BBHHB'
required_size = ustruct.calcsize(format)
if uart.any() >= required_size:
data = uart.read(required_size)
header,id,data,error_checking,trailer = ustruct.unpack(f'>{format}',data)
...and the above probably needs to live in some sort of loop.
I've been exploring the ADAM 6717 from Advantech.
This is the ModBus address table for said device:
At first I wanted to modify the value of the Digital output channel 0(DO0), so, as can be seen from the picture above, such address is the 0x0017.
I succeed at this by using a ModBus tool and the following settings:
Sending either "On" or "Off", turns On and off a LED connected to that output. Everything runs smoothly according to my expectation up to this point.
The problem arises when I want to read the Analog Input channel 6 or equivalently, address 400431~40044.
Since that address lies on the Analog Output Holding Registers part of the address table, I though that the following settings would accomplish the job:
However, as can be seen above, the reading shows 0.0 when there is actually 6V connected to that input (a potentiometer)
It is worth mentioning that I've made sure to enable the AI6 channel as well as setting it to Voltage mode instead of current. Also, the web utility for the device shows the AI6 reading correctly as I change the potentiometer's resistance value.
So the problem doesn't lie in the connection from the potentiometer to the AI6 but somewhere else.
Out of nothing and leaving aside what I think I know on this topic, I though of changing the function from 0x03 to 0x04
However, the response is exactly the same.
It bugs me that I can read and write values to the output coils but not the Analog output holding registers.
Is there any configuration that I might be missing over here?
Thanks in advance.
Device settings:
IP address: 10.0.0.1
Port in which the ModBus service is running: 5020
Hi I'm trying to get some measurement data from a ble decice and display it in my flutter app. I'm also using flutter_reactive_ble
I have two characteristics, one for reading and one for writing. I subscribe an event listener to the readCharacteristic and then I write a request just like below
_ble!.writeCharacteristicWithoutResponse(characteristicWrite, value: [0x99, 0x00, 0x19]);
As the value parameter i'm sending a list of hex value. Every value has it's role, as the ble's manual defines below:
I'm using the hex values of the manual's example, and the device sends me the 10 first measurements, which is correct, because every req response has maximum 10 measurements. The thing is that, in the scenario of having 20 measurements, I can't get the last 10. I tried of doing the following
await _ble!.writeCharacteristicWithoutResponse(characteristicWrite, value: [0x99, 0x00, 0x01, 0x99]);
I added 0x01 in the values list, because the manual says
value 1: continue with next group
But data is not getting sent.
How is it possible to get all the measurements, and further more, get for example the 5 last? Can anybody help me or give me a hint? Thank you for your time
The data always has to be 3 bytes long that you send. i.e.
[0x<header>, 0x<command>, 0x<checksum>]
In your second example you have too many bytes. It looks like you have an extra command. i.e.
[0x<header>, 0x<command>, 0x<command>, 0x<checksum>]
For the second write take out the 0x00 and make sure the checksum is correct. i.e:
[0x99, 0x01, 0x1A]
You send this second write after you receive the first 10 measurements
I have working C & Python3 code, based upon simple examples from the internet, where I can correctly send data from my Raspberry Pi4 to an Atmel SAM-E70 dev kit board. I've got a logic analyzer connected to look at the data being sent, and for every i2c_write_data_block() from my Python3 code, the smbus2 code sends the 7-bit address, followed by 0x00, followed by the byte stream that I want to send. My C code, sending the same byte streams, doesn't have the 0x00 between the address and the data. Finally, sending the byte stream using i2ctransfer() from the shell also works as expected: no extra byte.
Hypothetically, it could be that the smbus2 package is trying to use a 10-bit address, but I cannot find any documentation supporting this supposition. In fact, what I've found indicates that the I2C bus configuration is performed via config file(s) which would lead me to the believe that the language used to communicate on the I2C bus shouldn't matter - it would have the same configuration.
Has anyone else encountered this?
I noticed the same thing using the smbus2 i2c_write_data_block() function.
To avoid sending the 0x00 start byte, use the i2c_rdwr() function.
Example:
bus = SMBus(1)
address = 4
data = 'Some message'.encode()
msg = i2c_msg.write(address, data)
bus.i2c_rdwr(msg)
I would like to read a block of data from my Arduino Mega (and also from an Arduino Micro in another project) with my Raspberry Pi via I2C. The code has to be in Perl because it's sort of a plug-in for my Home-Automation-Server.
I'm using the Device::SMBus interface and the connection works, I'm able to write and read single Bytes. I can even use writeBlockData with register address 0x00. I randomly discovererd that this address works.
But when I want to readBlockData, no register-address seems to work.
Does anyone know the correct register-address, or is that not even the problem that causes errors?
Thanks in advance
First off, which register(s) are you wanting to read? Here's an example using my RPi::I2C software (it should be exceptionally similar with the distribution you're using), along with a sketch that has a bunch of pseudo-registers configured for reading/writing.
First, the Perl code. It reads two bytes (the output of an analogRead() of pin A0 which is set up as register 80), then bit-shifts the two bytes into a 16-bit integer to get the full 0-1023 value of the pin:
use warnings;
use strict;
use RPi::I2C;
my $arduino_addr = 0x04;
my $arduino = RPi::I2C->new($arduino_addr);
my #bytes = $arduino->read_block(2, 80);
my $a0_value = ($bytes[0] << 8) | $bytes[1];
print "$a0_value\n";
Here's a full-blown Arduino sketch you can review that sets up a half dozen or so pseudo-registers, and when each register is specified, the Arduino writes or reads the appropriate data. If no register is specified, it operates on 0x00 register.
The I2C on the Arduino always does an onReceive() call before it does the onRequest() (when using Wire), so I set up a global variable reg to hold the register value, which I populate in the onReceive() interrupt, which is then used in the onRequest() call to send you the data at the pseudo-register you've specified.
The sketch itself doesn't really do anything useful, I just presented it as an example. It's actually part of my automated unit test platform for my RPi::WiringPi distribution.