The scheduled command list tells the I/O template what to do and when to do it. It is an internal data structure that the program builds from operator input via a text file (CONFIG.TXT as the default). Every node of the command list must include:
- The period (how many cycles between transmissions of the command)
- The command itself
- The prefix and index of the ONSPEC table locations to place the results in, and usually some form of conversion option
Often more fields than this are necessary or desirable. In addition to these basic fields, pointer fields are generally included to allow easy movement through the nodes for the purpose of searching. To save memory in the case of small lists while allowing the flexibility of making the list as large as desired, the nodes are created dynamically.
This chapter will discuss the following aspects: