Use the Index Tabs above to Select both the Style of PC Slot and the Number of Ports Required.

All our serial expansion cards need to be plugged into the PC. This requires the removal of the lid, plugging in and securing the card, replacing the lid and powering up.

All cards plugged into a PC require software 'drivers' to run, these drivers will depend on both the type of card and the operating system. All our cards are supplied with the 'driver' software on a CD for most operating systems i.e. Windows95/98/ME/NT, Linux, Unix and DOS.

Before you order a card you need to know what type of 'Expansion Slot' there is available within your PC. Our range consists of 3 types of card fitting the 2 types of expansion slot, either ISA or PCI.

PCI Slot:
This is the more modern type of Slot. Our cards that use this type of slot are Plug-n-Play, which means that the driver software is generally very straightforward to install. This style of card is the much preferred and the more 'future proof', but does come with a slight increase in cost.

ISA Slot:
Original PC's were fitted with this type of slot, and many modern PC's are still fitted with one or two ISA slots for compatibilty with older expansion cards. The ISA slot cards are cheaper than PCI but may be a little more involved to configure. Our Budget range of cards uses only half of the full ISA slot and therefore only have the capacity to address up to IRQ 8 which can be a big restriction in some PC's.

The most common form of interface is RS232. This is the standard interface already used on COM1 and COM2 on the rear of most PC's. Our range of cards also includes RS422 and RS485 signalling for use in specialist applications.

Choosing the right serial card

Check out the following.

• Distance and environment. RS232 is really only good for runs up to around 50M with good cable and is susceptible to noise and interference when using long runs of poor quality cable. RS422 is good for long runs or wiring within an industrial environment. Wiring for RS422 requires the use of twisted pairs, like telephone cable, and dependant on the equipment at the other end may need conversion back to RS232. RS485 is very similar to RS422 but using a single twisted pair cable with multi-drop capability. RS485 is a very technical solution and should only be considered by the experienced.
• How many Ports. We can supply cards with just two ports up to cards with eight ports each. It is possible to plug in up to four of our cards into each PC, but check there is sufficient slots available first.
• Speed. All of our cards will run up to 115k baud but many operating systems hold up certain tasks causing loss of data. If it is likely to have several fast communications ports running on a slower computer it is best to have a large serial cache buffer to minimise this problem.
• IRQ usage. Many modern computers have very few IRQ lines available to use, which causes a problem with conventional serial ports which require a spare IRQ for each port. Our four and eight port cards only require ONE IRQ line, indeed up to four cards can be installed and still only need ONE IRQ line.
• Connector Style. Our 4-port and 8-port cards come with a choice of connector. The standard connection is using an adapter cable from a multi-pin connector on the card to a series of DB25 connectors on short fly-leads. An alternative is an expansion box with four / eight connectors firmly mounted on the box. Another alternative for some RS232 cards is a series of RJ-11 or RJ-12 connectors, which are actually mounted on the card edge.