Tutorial how to set up a aliexpress industrial modbus display.
Usually you can search for following listings: “0.56 in 4 Digit LED Display RS485 Serial Port Meter Communication RTU/ASCII Protocal”
So first the specs:
- Support ASCII text and RTU dual protocol automatic identification, no user setting in required.
- The meter can display 4 digit of serial port.
- Wide range of power supply voltage between DC7~36V.
- Large 0.56inch display area for only 4 digit ,more clear.
- The baud rate can be 1200bps/2400bps/4800bps/9600bps/19200bps/38400bps/57600bps/119200bps.
- Price 10-15 USD (12.2021)
Because display will come without any manuals or information, it was quite a hassle to find good information about the display.
Things we need:
1 ) RS485 TO USB converter
2 ) QModMaster Software https://sourceforge.net/projects/qmodmaster/files/
3) Termite Terminal https://www.compuphase.com/software_termite.htm
From behind without the cover the display looks like following:
Connect your RS485 converter with display. B- with B- and A+ with A+
Connect power for the display.
If RS485 converter is recognised by your computer, we can continue.
Lets open TermiteTerminal software:
Open settings and configure like following, remember to use right COM port:
Now we will ASCII mode to communicate with the display.
Try out following commands to make sure the connection between computer and display is established.
Serial response test: $001,01& Check digital mode: $001,02&
If you receive following answers everything works as it should:
You can use ASCII to control the display:
Displays 12.14 $001,12.14& Displays abc $001,abc$
If everything worked we can proceed with the next step.
Close the Termite software.
Lets open QModMaster software:
Next lets configure QModMaster settings. Check on which COM port is used for the RS485 converter.
In QModMaster go “Options” -> “Modbus RTU”. Except for COM port your settings should be following:
Input Settings and click “OK”.
Now click on small connect icon:
Display modbus registers are following:
Slave Addr: 1
Start Address: 4
Slave Addr: 1
Start Address: 0
So inserting 2 to the register 4 and 1001 to register 0 and writing the values will show 10.01:
You can also use multiple registers to indicate values on the display.
Slave Addr: 1
Start Address: Hex:0x90 / Dec:144
Number of Registers: 2
Values 2 and 1001 will display 10.01
Values 1 and 6006 will display 600.6
The first register is used for indicating decimal point and sign. Hex values for different options are as following:
00XX = +
01XX = –
XX00 = xxxx
XX01 = xxx.x
XX02 = xx.xx
XX03 = x.xxx
And that is it.
Additional information found on internet: