Image forming apparatus capable of displaying on display error relating to drum cartridge in preference to error relating to toner cartridge

1. An image forming apparatus comprising:

a main casing;

a drum cartridge attachable to and detachable from the main casing, the drum cartridge including a photosensitive drum and a drum memory;

a toner cartridge attachable to and detachable from the drum cartridge, the toner cartridge including a toner memory;

a display; and

a controller,

wherein the controller is configured to:

determine whether an error occurs in the drum cartridge through a communication with the drum memory;

determine whether an error occurs in the toner cartridge through a communication with the toner memory; and

when determining that an error occurs in the drum cartridge and determining that an error occurs in the toner cartridge, display on the display an error relating to the drum cartridge in preference to displaying on the display an error relating to the toner cartridge.

2. The image forming apparatus according to claim 1 ,

wherein the controller is configured to communicate with the toner memory through the drum cartridge when the toner cartridge is attached to the drum cartridge.

3. The image forming apparatus according to claim 2 ,

wherein the drum cartridge further includes a substrate, and

wherein the controller is configured to communicate with the toner memory through the substrate.

4. The image forming apparatus according to claim 3 ,

wherein the substrate includes the drum memory, and

wherein the controller is configured to communicate with the drum memory through the substrate.

5. The image forming apparatus according to claim 4 ,

wherein the controller is configured to:

attempt to communicate with both of the drum memory and the toner memory; and

when failing to communicate with the drum memory and succeeding in communicating with the toner memory, display on the display an error indicating that the substrate is abnormal in preference to displaying on the display an error relating to the toner cartridge.

6. The image forming apparatus according to claim 1 ,

wherein the controller is configured to:

attempt to communicate with both of the drum memory and the toner memory; and

when failing to communicate with both of the drum memory and the toner memory, display on the display an error indicating that the drum cartridge is not attached in preference to displaying on the display an error indicating that the toner cartridge is not attached.

7. The image forming apparatus according to claim 6 ,

wherein the controller is configured to:

when succeeding in communicating with the drum memory, attempt to authenticate the drum memory; and

when failing to authenticate the drum memory, display on the display an error indicating that the drum cartridge cannot be recognized in preference to displaying on the display an error relating to the toner cartridge.

8. The image forming apparatus according to claim 7 , further comprising a main memory,

wherein the controller is configured to:

when succeeding in authenticating the drum memory, read data stored in the drum memory from the drum memory;

determine whether a type of the drum cartridge indicated by the read data matches a type of the drum cartridge indicated by data stored in the main memory; and

when determining that the type of the drum cartridge indicated by the data does not match the type of the drum cartridge indicated by the data stored in the main memory, display on the display an error relating to the type of the drum cartridge in preference to displaying on the display an error relating to the toner cartridge.

9. The image forming apparatus according to claim 1 ,

wherein the toner cartridge further includes a developing roller.

10. The image forming apparatus according to claim 1 ,

wherein the controller is configured to determine whether an error occurs in the toner cartridge even in a case where the controller determines that an error occurs in the drum cartridge.