Hi, you can use a Prgarm flow chart to show that data transfer between systems. Each transition can be shown as an interface object implemented by an application. The application is modeled as usual using an access diagram. Here you create a link to the hardware components as well.
The Program Flow Chart works well - Just a few tips when I have implemented this type of model for clients. Remember you can use a Derived model type - named for the purpose and with the objects you are interested in.
Also sometimes clients may find the model too 'cluttered' so we have used a template that reduces the Data object to be as small as possible and put the name below the object. In this way, it looks like two objects (such as an Application System) with a line between the object with the name of the data being transferred between the systems below the connecting line.
Also using templates you can define different colored lines to indicate different types of transfers between application systems (eg - batch updates, on-demand and manual upload). The connection then has to be directly between the application systems.
Thanks - Lara