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4-8 Using the MintMT ActiveX Control

4.7 Limitations of PC based applications

4.7.1 Events

There are a number of event types supported by MintMT such as ONERROR, FASTIN, TIMER, etc.

These events are only supported by NextMove PCI. Serial controllers do not support MintMT events on

the PC application. See section 5.1 for more detail on using events.

4.7.2 Execution Speed

Commands called from the PC application execute slower than if called directly on the controller. See

section 9-1 for example timings.

The PC application function calls will not take priority over a MintMT program running on the controller, the

processing of function calls will be shared. The MML Interface will process a MML function call request

from MintMT followed by an external request. Running a PC application that communicates with the

controller while also running a MintMT program will result in both applications running slower than if they

were executed separately.

The MintMT program will be slowed due to the sharing of the MML Interface with the ICM function calls

from the PC application and the overhead of processing the ICM packets.

On serial controllers the baud rate at which the serial communication is running affects the impact that the

PC application can have. The higher the baud rate the more characters can be sent to the controller. This

results in faster ICM function calls from the PC application but will cause any MintMT program to run more

slowly. Conversely, the lower the baud rate the slower the character transmission rate to the controller.

This results in slower ICM function calls from the PC application, but gives more CPU time to the MintMT

program.

On Dual Port RAM controllers such as NextMove PCI, the ICM data is transferred to the controller over

Dual Port RAM. This is shared memory and the PC can write to this without affecting the application

running on the controller. When an ICM transaction occurs over Dual Port RAM the PC writes the function

call details before interrupting the controller. This means the processing overhead of ICM function calls on

Dual Port RAM controllers is significantly lower than on serial controllers.

4.8 Extended functionality of DPR controllers

Dual Port RAM controllers are resident within the PC. Rather than using a serial communication link to the

PC like RS232 or RS485 they use Dual Port RAM. This is an area of shared memory on the controller that

both the PC and the controller can access.

The PC can read and write to Dual Port RAM at the same time as the controller, the controller can be

reading one block of data while the PC is writing another. This allows much faster data transfer than on a

serial controller.

As the controller is resident within the PC certain locations of Dual Port RAM act as interrupt locations so

an application on the controller can interrupt the PC or, an application on the PC can interrupt the

controller. This allows support for MintMT events in a PC application.

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Mint NextMove PCI Manual de usuario Pagina 18