1.  Field of the Invention
The present invention relates to an image forming apparatus, such as a copier and a printer, a method for controlling the image forming apparatus, and a program and, in particular, to technology for setting a transport speed of a recording medium to a peripheral unit, such as a paper feeder unit. 
2.  Description of the Related Art
Known is an image forming apparatus that includes a plurality of paper feeder units for selectively feeding recording media (recording paper) of different types having different sizes and materials.  Also, some image forming apparatuses optionally provide the paper feeder units of this type in order to reduce user costs. 
Such an optional paper feeder unit has been developed for each type of image forming apparatus due to differences between transport speeds and between transfer sequences of recording paper in the main bodies of the image forming apparatuses.  However, in recent years, a variety of methods for setting a transport speed has been discussed to commonly use the optional paper feeder unit in a variety of image forming apparatuses having different transport speeds as follows. 
For example, Japanese Patent Laid-Open No.  05-000538 discloses technology in which an image forming apparatus instructs a transport speed to an optional paper feeder unit each time recoding paper is fed and technology in which a transport speed is switched by a dip switch mounted on the optional paper feeder unit.  Additionally, Japanese Patent Laid-Open No.  08-328445 discloses technology in which data concerning overall system control including a moving speed of a photoconductor, positional information about paper sensors and a registration roller in a paper transfer path, a paper feed speed, and a paper transport speed are transmitted to an optional paper feeder unit in advance.  Furthermore, Japanese Unexamined Utility Model Registration Application Publication No.  05-068977 discloses technology in which, when optional paper feeder units in different tiers have different transport speeds, the transport speeds are determined in advance. 
However, in the technology in which a transport speed is instructed each time recoding paper is fed, the time for instructing the transport speed is required, and therefore, the transfer control cannot be speeded up.  In the technology in which a transport speed is switched by a dip switch, complex software for supporting the transport speeds and transfer sequences for a plurality of models is required in the main body of the image forming apparatus, and therefore, an amount of memory for the software increases and the cost increases. 
In the technology in which data concerning overall system control is transmitted to an optional paper feeder unit in advance, complex software for analyzing the data while considering all data for the control is required in the optional paper feeder unit, and therefore, the cost increases. 
Still furthermore, in the above-described known technologies, it is sometimes difficult for the image forming apparatus itself to change a transport speed and a transfer sequence in accordance with the type of recording paper (e.g., a material and a size) and the performance of forming an image (e.g., a resolution and a color mode).