Arduino GSM USSD AT-Command回复为空

Question

我有这个arduino代码。GSM盾牌连接上了，ussd也在发送，但我没有得到任何回复(比如“ok”)。ussd短码是有效的。这里我漏掉了什么？或者是我的代码中有错误？(设备: Arduino Uno，GSM shiled)

感谢您对这件事的任何见解。谢谢

#include <GSM.h>
#include <GSM3ShieldV1DirectModemProvider.h>

// initialize the library instance
GSM gsmAccess;  

GSM3ShieldV1DirectModemProvider modemAccess;


// PIN Number
#define PINNUMBER ""


void setup() {   
   Serial.begin(9600);  
   // initialize the digital pin as an output.  
   Serial.println("GSM networks scanner");

   connectGSM();

   String At_COMMAND = "AT+CUSD=1,\"*#456#\"";   
   Serial.println("Sending At command");
   String reply = modemAccess.writeModemCommand(At_COMMAND,15);
   Serial.println("Sent");
   Serial.println(reply);
   Serial.println("Sent");  
}

void connectGSM(){
  boolean notConnected=true;
  Serial.println("Connecting...");
  while(notConnected){
    if(gsmAccess.begin(PINNUMBER) == GSM_READY)
      notConnected = false;
    else delay(1000);
  }
  Serial.println("Connected to GSM");
}

输出

GSM networks scanner
Connecting...
Connected to GSM
Sending At command
Sent

Sent

Answer 1

尝试将时间从15毫秒增加到1000毫秒