|
|
 |
The comparison table below indicates when and how to use the classic
boards or the intelligent boards according to your application and to
your needs.
This table works as well for the synchronous and the asynchronous communication
modes.
|
Application type
|
|
|
|
On-board programming
|
NO |
YES |
|
Determinism
|
YES
(1) |
YES |
|
|
YES
(1) |
YES |
|
Accurate events dating
|
NO
(2) |
YES
(2) |
|
Complex protocols
|
NO |
YES |
|
Slow and/or overloaded OS
|
NO |
YES |
|
High speed without protocol
|
YES
(3) |
YES |
|
High speed with protocol
|
NO |
YES |
|
Very high speed without protocol
|
YES |
YES |
|
Very high speed with protocol
|
NO |
YES |
|
Large number of ports (4)
|
NO |
YES |
| (1) |
If allowed by the operating system, this is true for
most Real Time Operating Systems (eg: QNX
6 NEUTRINO, VxWorks, Real Time LINUX ...), this is not true for Windows & Linux. |
| |
|
| (2) |
Accurate dating of events (near the micro-second)
cannot be achieved with a classic board because the dating operation
must be done by the operating system itself. MCX-PCI
intelligent boards feature an on-board 32 bits timer counter dedicated
to such operation. |
|
|
| (3) |
However, exchanging of back to back frames can only be suitably
supported by a Real Time Operating System on the host computer (eg: Real Time LINUX).
|
|
|
| (4) |
It is implicit that the relationship between communication speed
and number of ports is a determining factor in the choice of the
type of board.
More the speed will be raised and less the board will be able to
support a large number of ports.
An intelligent communication board is recommended for such applications.
|
|
Lexicon of
employed terms
|
| Classic board |
We consider a classic board as a synchronous
or asynchronous board not featuring an on-board micro-processor dedicated
to local information processing (eg: xRS-PCI,
xRS-UNI,
UNX-PCI). |
|
|
| Intelligent board |
We consider an intelligent board as a synchronous
or asynchronous board featuring an on-board micro-processor dedicated
to local Protocol processing (eg: MCX-PCI). |
| |
|
| Determinism |
Means that the execution time must be known and stable,
but by necessarily very fast. |
| |
|
| Low
latency |
Very short response time of the application
to physical events. |
| |
|
| High speed |
Binary rate near 4 Mbps. |
| |
|
| Very high speed |
Binary rate higher than 10 Mbps (eg: HSSI,
52 Mbps). |
| |
|
| Slow and/or overloaded OS |
It is an operating system like Windows whose
architecture does not allow a great reactivity for the communication
applications and especially since such systems are rarely dedicated
to the communication application. |
| |
|
| Complex protocol |
We consider a complex Protocolas a Protocol
which requires a lot of CPU power processing (eg: X25) and in opposition
to a low level Protocol like HDLC. |
|
|
