ZQ310 bluetooth error not intercept


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Hi, we are working on Android 11 with link-os SDK 2.14.5198.
The system developed to print travel tickets is based on the fact that the printer prints and does not return any printing errors.
We check the printer status before printing, send it to print, wait 500ms and double check the printer status to verify that no errors have occurred.

A user sent the print, the printer did not print, did not return any errors and the title ended up in the purchase table and should not have seen it did not print but I did not catch any errors.
What could have happened and why was I unable to intercept the problem?
At the code level I took the one provided in the documentation of the sdk for checking the printer status.
We use variable status to register the error or the status 1 that is printed.
So this is the code:
1) Method to start Print:

private int connectAndSendLabel(final String mac, String dataPass, String type, String url, String printerType) {

printerConnection = new BluetoothConnection(mac);

int Status = 0;
try {
printerConnection.open();
ZebraPrinter printer = null;

if (printerConnection.isConnected()) {
printer = ZebraPrinterFactory.getInstance(printerConnection);

if (printer != null) {

Status = sendTestLabel(dataPass, type, url, printerType);
printerConnection.close();
}
} else {
Status = -5;
}
} catch (ConnectionException e) {
Status = -2;
} catch (Exception e) {
e.printStackTrace();
Status = -4;
} finally {
return Status;
}
}

2) Method to sent title to printer:

private int sendTestLabel(String dataPass, String type, String url, String printerType) throws Exception {
int Status = 0;
Status=checkPrinterStatus(printerConnection);

if (Status == 1) {
try {
String s = createZplReceipt(dataPass, type, url, printerType);

byte[] configLabel = s.getBytes();

printerConnection.write(configLabel);

if (printerConnection instanceof BluetoothConnection) {
DemoSleeper.sleep(500);

Status=checkPrinterStatus(printerConnection);
}

//buffer reset to deny reprint
if (Status == 2 || Status == 3 || Status ==4 || Status == -1 || Status == -2 || Status == -3) {
String reset ="~JA";
byte[] buffreset = reset.getBytes();
printerConnection.write(buffreset);
}

} catch (ConnectionException e) {
Status = -2;
}
}
return Status;
}

3) method to check printer status.

public int checkPrinterStatus(Connection conn) throws Exception {

int status = 0;
try {
ZebraPrinter printer = ZebraPrinterFactory.getInstance(conn);

PrinterStatus printerStatus = printer.getCurrentStatus();

Boolean paused = false;
Boolean HeadOpen = false;
Boolean PaperOut = false;
Boolean PrintOk = false;

if(printerStatus.isReadyToPrint){
PrintOk = true;
}

if(printerStatus.isPaused){
paused = true;
}
if(printerStatus.isHeadOpen){
HeadOpen = true;
}
if(printerStatus.isPaperOut){
PaperOut = true;
}

if (PrintOk) { //print ok
status = 1;
} else if (paused && !HeadOpen && !PaperOut){ //pause print
status = 2;
} else if (paused && HeadOpen && !PaperOut){ //
status = 3;
} else if (paused && !HeadOpen && PaperOut){ //paper empty
status = 4;
} else { //all other cases
status = -1;
}

} catch (ConnectionException e) {
e.printStackTrace();
status = -2;
} catch (ZebraPrinterLanguageUnknownException e) {
e.printStackTrace();
status = -3;
} finally { }
return status;
}

Have you some suggestions ?
Thanks

Submitted by James Swinton … on April 04, 2022 Permalink

Hi,

It's possible that the file was sent to the printer, but the connection was closed before the file transfer was complete. When the error occurred, was the file larger than usual?

Perhaps try increasing the sleep time in your application to see if this resolves the issue.

Submitted by SSi1 on April 04, 2022 Permalink

As James has pointed put, the connection is closed right after the call to the sendTestLabel() without checking the Status variable in your connectAndSendLabel() function. Suggest to check the printer status or add some delay before calling the printerConnection.close().

Without checking the status after calling the printerConnection.write(buffreset) or add some delay before calling the printerConnection.close() is likely the root cause of the issue you've described.