I am trying to communicate with a battery charge controller via RS-485 ModBus RTU half-duplex communication. I am using a Particle Argon and this RS-485 transciever. I can see that the Tx packet is correct and being sent. However, I am getting no response. The charge controller is powered separately so only the A,B, and GND lines are connected.

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#include "Particle.h"

SYSTEM_MODE(SEMI_AUTOMATIC); 
SYSTEM_THREAD(ENABLED);

//instantiate ModbusMaster object as slave ID 1
ModbusMaster node(1);
unsigned long interval = 0;
unsigned long base_T = 1000;
const int addr = 0x30A0;

void idle() {
    delay(10); // in case slave only replies after 10ms
}

void setup() {
    // initialize Modbus communication baud rate
    node.begin(9600);
    node.enableTXpin(D4); //D7 is the pin used to control the TX enable pin of RS485 driver
    node.enableDebug();  //Print TX and RX frames out on Serial. Beware, enabling this messes up the timings for RS485 Transactions, causing them to fail.
    node.idle(idle);      //function gets called in the idle time between transmission of data and response from slave

    Serial.begin(9600);
    // while(!Serial.available()) Particle.process();
    Serial.println("Starting Modbus Transaction:");
}


void loop() {
    uint8_t j, result;
    uint16_t data[10];

        if (millis() - interval > base_T) {
                interval = millis();
        result = node.readInputRegisters(addr,1);
    
    
    // do something with data if read is successful
    if (result == node.ku8MBSuccess) {
        Serial.print("Success, Received data: ");
        for (j = 0; j < 2; j++) {
            data[j] = node.getResponseBuffer(j);
            Serial.print(data[j], HEX);
            Serial.print(" ");
        }
        Serial.println("");
        base_T = 1000;
    } else {
        Serial.print("Failed, Response Code: ");
        Serial.print(result);
        Serial.print(" - ");
        Serial.print(result, HEX); 
        Serial.println("");
        base_T = 5000; //if failed, wait for bit longer, before retrying!
    }
    }
}
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Does anyone experience using this transceiver or debugging the RS-485 bus? I’ve used a logic analyzer to confirm that the transmitted packet looks as expect leaving the micro but am not sure what to expected the A,B lines of the RS-485 transciever to look like.