LED 7 Segment Display, MODBUS-RTU Display Module, 4 Digits Display with RS485 Serial Port for PLC Communication (5-36V)

worked great

No documentation. imposible to set it up.

Scoured the web for a manual for this thing but had no luck. Eventually figured it out so I thought I'd share for everyone else on here:You have to use the corresponding modbus holding registers to assign the parameters listed in the directions.register 1 is for the data bits. These are the values that will appear on the displayregister 2 is for the decimal position. 00= XXXX, 01= XXX.X, 02= XX.XX, 03= X.XXXregister 3 is for the brightness. 00 is the dimmest and 07 is the brightestregister 4 is for the baud rate. 00 = 1200, 01 = 2400, 02 = 4800, 03 = 9600,. etc..Hopefully this will save you some time.Here is a sample of the code I used to test it out:#include <ModbusMaster.h>// Modbus slave ID#define SLAVE_ID 1// Number of registers to send#define NUM_REGISTERS 4// Modbus address for each register (1-4)#define REGISTER_1 0x0000#define REGISTER_2 0x0001#define REGISTER_3 0x0002#define REGISTER_4 0x0003#define RS485SerialTxPin 6#define RS485SerialRxPin 7// Define the array to store data for each registeruint16_t holdingRegs[NUM_REGISTERS];// Modbus objectModbusMaster node;void setup() {Serial.begin(9600); // Start the serial communicationnode.begin(SLAVE_ID, Serial);// Initialize the holding registersholdingRegs[REGISTER_1] = 05; //data bitholdingRegs[REGISTER_2] = 01; //decimal positionholdingRegs[REGISTER_3] = 07; //brightnessholdingRegs[REGISTER_4] = 03; //baudrate}void loop() {// Update the data in the holding registersholdingRegs[REGISTER_1] = 05;holdingRegs[REGISTER_2] = 01;holdingRegs[REGISTER_3] = 07;holdingRegs[REGISTER_4] = 03;// Send the holding register data to Modbus registersfor (int i = 0; i < NUM_REGISTERS; i++) {node.writeSingleRegister(i, holdingRegs[i]);delay(10); // Add a short delay to prevent communication issues}// Your additional code can go here}

Item arrived with no documentation whatsoever. Product listing has insufficient information.back it goes.

I was stuck in a dead end using this until other reviews provided test code. My particular test involved using different tx and rx pins for my breakout board on an arduino but the display now works great.