À propos des liaisons série
Une méthode privilégiée pour établir la communication entre le système CS90 et les périphériques consiste à utiliser des liaisons série. Plusieurs normes de liaison série sont disponibles, chacune avec des qualités différentes.
Sauf indication contraire, ces câbles doivent être fournis par le chantier d'installation.
Interface série RS-232
La longueur maximale pour un câble série RS-232 est généralement de 60 mètres avec un débit de données de 2 400 bps, mais cela dépend de la qualité du câble. Toujours vérifier les indications des fabricants de câbles pour la capacité de dérivation réelle. Un chiffre courant est de 47,5 pF/m, ce qui donne une longueur de câble maximale d'environ 50 mètres.
Note
La plupart des câbles RS-232 ne sont pas compatibles avec tous les signaux de la norme RS-232 standards. Notez qu'une grande longueur de câble non blindé attrapera le bruit plus facilement. Ceci est dû à un déséquilibrage des signaux RS-232.
Même si une norme existe pour la configuration des broches du RS-232 RS, certains fabricants peuvent toujours choisir leurs propres broches de connecteur pour les différents signaux utilisés. Afin que la connexion du RS-232 à votre périphérique se fasse correctement, vous devez toujours consulter les instructions du fabricant de l'appareil.
Pour de plus amples informations sur les interfaces série standard RS-232, voir (par exemple) :
Interface série RS-422
While RS-232 is the most common serial interface for communicating with external devices using the NMEA standard, it only allows for one transmitter and one receiver on each line.
RS-422 provides a mechanism for transmitting data up to 10 Mbits/s. This interface format uses a balanced signal on two wires. This increases both the maximum baud rate and the physical length of the cable, and it reduces the noise. With a high quality cable, you can use RS-422 on distances up to 1500 meters even in noisy environments. RS-422 is also specified for multi-drop applications. This means that one transmitter can send data to up to 10 receivers.
Note
There are no common standard for RS-422 pin configuration. Any manufacturer may choose their own connector pins for the various signals used. In order to make the RS-422 connection to your peripheral device work properly, you must always consult the relevant instructions provided by the device manufacturer.
Utilisez un câble à paires torsadées.
For more information about the RS-422 serial communication standard, see (for example):
Interface série RS-485
RS-485 (also known as TIA-485–A) is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems. The standard is published by the Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA). Digital communications networks implementing the RS-485 standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multi-drop configuration.
RS-485 offers data transmission speeds of 35 Mbit/s up to 10 m and 100 kbit/s at 1200 m. Since it uses a differential balanced line over twisted pair (like RS-422), it can span relatively large distances (typically up maximum 1200 m). In contrast to RS-422, which has a single driver circuit which cannot be switched off, RS-485 drivers need to be put in transmit mode explicitly by asserting a signal to the driver. This allows RS-485 to implement linear bus topologies using only two wires. The equipment located along a set of RS-485 wires are interchangeably called nodes, stations or devices.
RS-485, like RS-422, can be made full-duplex by using four wires. Since RS-485 is a multi-point specification, however, this is not necessary in many cases.
Note
There are no common standard for RS-485 pin configuration. Any manufacturer may choose their own connector pins for the various signals used. In order to make the RS-485 connection to your peripheral device work properly, you must always consult the relevant instructions provided by the device manufacturer.
Utilisez un câble à paires torsadées.
For more information about the RS-485 serial communication standard, see (for example):