How to listen for USB Alerts | Developer Portal

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Accepted Solution

S Steven Si 4 months 4 weeks ago

We don't have sample code on how to receive alerts. For USB, however, you would have to create a USB connection with the API from the Link-OS SDK, and then monitor the alerts sent from the printer over USB (i.e., reading from the USB connection (i.e., connection.read()) in a loop) to receive alerts.

7 Replies

S Steven Si 4 months 4 weeks ago

S SDK NDD 4 months 4 weeks ago

Hi,

I will try using the connection.read() loop.

About configuring the Alert, how do we set up the PrinterAlert constructor to configure for a USB connection?

I tried the way below but it did not work, maybe I am passing incorrect values to the constructor?

PrinterAlert alert = new PrinterAlert(AlertCondition.HEAD_OPEN, AlertDestination.USB, false, false, "", 0, false);

I suspect of parameters 5 and 6.

Parameter 5 asks for a String for destinationAddress and parameter 6 for an Int for Port, but we are not sure if this is right since it is a USB connection.

Best regards,

S Steven Si 4 months 3 weeks ago

The parameters for the IP address and the port number will be ignored if the alert destination is USB. If you want to get alerts for the HEAD OPEN on set and on clear, you will need to pass true to the onSet and onClear parameter (as shown below)

// Define the alert to monitor
PrinterAlert  alert = new PrinterAlert(AlertCondition.HEAD_OPEN, AlertDestination.USB, true, true, "", 0, false);

// Configure the printer with the defined alert
printer.configureAlert(alert);

S SDK NDD 4 months 3 weeks ago

Hi Steven,

I am trying to run the code below on a ZD230 like this:

    public static void ConfigureAlerts(DiscoveredPrinterDriver printer) {
       Connection connection = null;
       try {
           connection = printer.getConnection();
           connection.open();
           ZebraPrinter genericPrinter = ZebraPrinterFactory.getInstance(connection);
           ZebraPrinterLinkOs linkOsPrinter = ZebraPrinterFactory.createLinkOsPrinter(genericPrinter);
           
           PrinterAlert alert = new PrinterAlert(AlertCondition.HEAD_OPEN, AlertDestination.USB, true, true, "", 0, false);
           linkOsPrinter.configureAlert(alert);
       } catch (Exception e) {
           logMessage("Error " + e.getMessage());
       } finally {
            connection.close();             
       }
   }

but its giving the following error:

Cannot invoke "com.zebra.sdk.printer.ZebraPrinterLinkOs.configureAlert(com.zebra.sdk.printer.PrinterAlert)" because "linkOsPrinter" is null

Running the same code in a ZT231 works as normal, do you know why is that?

Best regards.

S Steven Si 4 months 3 weeks ago

The ZD230 is not a Link-OS printer. It's a Link-OS Basic printer. The following statement is only applicable to Link-OS printers. If it used for a non Link-OS printer or a Link-OS Basic printer, a null pointer will be returned.

ZebraPrinterLinkOs linkOsPrinter = ZebraPrinterFactory.createLinkOsPrinter(genericPrinter);

S SDK NDD 4 months 3 weeks ago

Does this mean that Link-OS Basic printers do not have the Alerts system that can be captured? or does this mean that for getting the alerts from that device we can't use the above code and therefore if we want to configure and listen for alerts for this device, we need to use other methods? like connecting the printer via network and accessing the MIB?

S Steven Si 4 months 3 weeks ago

Alerts are supported on both Link-OS and Link-OS Basic printers. With Link-OS Basic printers, we have to stick with the ZebraPrinter instance to communicate with the printer, as we cannot use the ZebraPrinterLinkOs instance. Unlike the ZebraPrinterLinkOs, which has convenient alert methods, the alert configuration with the ZebraPrinter instance can be done via the SGD commands.