Appendix A: How to troubleshoot SE 79:04
These errors will most likely only happen in very specific corner cases that have not been identified during the development or the qualification of the printer, so normally, they do not severely impact the customer, as they do not affect their regular working flows.
Symptoms
The symptoms here are as numerous as the number of possible interactions between the user and the printer. In any case, it’s possible to identify the steps that caused the error to occur and avoid them as the steps will always be the same with no variance.
Important: An major element in determining the error is what the state the printer was in at the time the error was displayed. Actions the user has made when the printer is drying for example can produce an error, whereas the same action when the printer is doing something else (or is idle) may not produce any errors.
Solutions and workarounds
The recommended action plan in these cases is to identify the previous steps that caused the error and:
1Escalate the issue to the GBU through the GCC in order to have it corrected in the firmware.
2Recommend to the customer that they try to avoid the same steps to prevent the issue
3If the conditions that cause the error are in the customer’s regular workflow, try to identify a different way of achieving the same result out of the printer.
Random SE79:04: Concurrence issues and memory leaks
Some 79:04 errors happen randomly when the printer is being heavily used. However, it’s impossible to find a single set of conditions that reproduce the problem. It just happens from time to time, without a defined pattern.
These random 79:04 can have two different types of root causes:
Memory leaks: before a program is executed, it allocates the memory it will need. After the execution is complete, the allocated memory is freed to be used by other programs. If the allocation or the release of the memory are not properly programmed, every time the program is executed some memory will be incorrectly labeled (either as used or as free). This is known as a memory leak. When a program with a memory leak is executed a lot, the memory becomes progressively full (since it is not properly freed). When the leak becomes too big, the printer is left ‘out of memory’ to execute new processes and a 79:04 is triggered
Concurrence issues: there are certain resources that can be accessed by multiple programs or by multiple executions of the same program (what is known as multiple threads). Access to these resources must be correctly controlled to prevent unexpected behavior. Issues caused by an incorrect control of these resources are concurrence issues.
In the following you have a simple example: let’s imagine that there is a counter that controls the communication between the JetDirect card and the printer’s firmware. Whenever a new packet of information is sent by the JetDirect card to the printer, the counter increases. When the printer receives the packet and processes it correctly, the counter decreases. Another process
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