OP232/D'x' opto isolators provide 'complete' electrical isolation for serial connections using the RS232/V24 standards.

• 'Complete' means sub-pico Farad total capacitance, and isolation resistance of 10¹² ohms typically. There are no transformers or capacitors, only optical data paths, so all lines including ground are broken.

• No external power supplies are needed in normal installation as power is drawn from the signal lines themselves. A power pin is provided at either end to allow power to be supplied separately in special circumstances.

• Full duplex operation is provided with two options; model D1 provides Transmit (TX) and Receive (RX) lines (3 wire interface), and model D2 adds a control pair wired as CTS/RTS (5 wire interface).

• 38.4kbaud is achieved in all circumstances. All units are tested at 20kHz. They will clock faster in most situations, the speed limitation is the tolerance of the UARTS to small delay asymmetries introduced by optical coupling.

• Connection is by standard 9 way D connectors, one male, one female, moulded into the body. The device is wired 'straight through' so that for a standard connection it is only necessary to open an existing connection and insert the OP232 device.

RS232 is ubiquitous, but the standard itself can be a bit of a problem. The main difficulty is that RS232 takes system ground outside the computer.

The computer exports its clock noise, possibly making it impossible to use with sensitive measuring instruments.

A path is created back into the computer by which external electrical faults can do extensive damage.

Probably worst of all ground loops are created, often preventing communication at all, and causing all sorts of other problems.

OP232 devices prevent all these problems, often making RS232 viable and the most direct and cheapest solution.

Applications include;

• Isolation of noise affecting measuring instruments in medicine, geophysics, sound recording etc..

• Computer protection.

• Installation of long cable runs in industrial control and communication.

• Connection of Point-Of-Sale terminals to vending or weighing equipment in warehousing or vehicle fuel (Petrol/Gasoline) pumps.

Note the symbols << and >> show the direction of data flow. CTS/RTS are not active on D1 (single duplex) devices. Since each side is completely isolated, power for a side's outgoing line(s) is provided by incoming lines on the same side. Power is only needed if the voltage level on the incoming line is too low (<approx 7 volts 0-p). If external power is provided this is between GND and POWER (8 to 18 V nominal of either polarity, or AC). It will power only that side.

Cabling to enable most adaptations is available off the shelf, please enquire.

Contact us to pay using Google Checkout for other quantities / configurations or delivery outside the UK

Prices below are per unit ex-factory Exeter UK. They do not include shipment, VAT, or any other applicable taxes. Pricing in other currencies will be set at date of order. Prices below valid from 01.05.2007

UK delivery is normally by INTERLINK next-day at £8.50 for up to 2 units, £13.50 for all other single delivery quantities. Next day delivery can be arranged into most of Northern Europe.

These devices are manufactured to very high quality standards, and offer a degree of protection that is difficult to measure with standard instruments. The insulation resistance is typically 10,000 better than is measurable with insulation testers. Even with capacitance below 1pF, coupling by this means is higher than by conduction, even at mains supply frequencies. If the connecting cables to either side are laid over each other, coupling through the insulation will be the dominant mechanism.

We do not set or publish a voltage rating, since RS232 is a standard which has its ground connections exposed at either end. Therefore, a situation where any substantial voltage existed between these grounds by design would almost certainly contravene local electrical safety regulations. We can state that all units are tested at 1kV prior to shipment, and exceed our lower limit of 2 x 10¹¹ ohms at this voltage, and typically return 3 x 10¹² ohms. The isolators used have a manufacturers rating of 10kV. This statement implies no fitness for any purpose at any unsafe voltage.

These devices have already received type approval for certain specialist applications, and we believe will exceed any required statutory levels be such a margin, that they may be submitted for any local approvals with very considerable confidence.

They are CE marked as complying with EU regulations for EMC. We will continue to seek approvals for other national regimes, and this data sheet will be updated as appropriate. There are however no appropriate standards at present for this function, and it will normally be easier for a user to obtain approvals appropriate to an application by direct testing and local certification by appropriately qualified personnel.

These units are not authorised for use in life-support systems, or any other application where failure of these devices, or any aspect of use of these devices might lead to death or injury. Scimar Engineering Ltd will not accept any liability whatsoever for any form of loss or injury resulting from any aspect of the use of these devices.

This document nor any other publications from the company represent any statement of fitness of purpose for any application.

Applications are so numerous and the potential hazards from mis-use so varied that we could not make any such statement. Where there is any question of hazard to human health or life the application must be checked by locally qualified engineers and certified by them as safe and complying to local regulations.

Since these devices are fully potted (and thus any faults impossible to diagnose), and should properly be considered as having fulfilled their function if destroyed by fault voltages, we restrict ourselves to a six month formal warranty (except where sales law decrees otherwise) against failure due to defects, workmanship etc.

We have had the case of a gentleman with a CADCAM computer connected via our previous model isolator to an NC controlled plasma cutter. Some part of the cutter went up in smoke, which had previously signalled the need for an expensive rebuild of the computer. He phoned to say he was delighted that our isolator had this time saved this expense, and to enquire whether we thought it likely that our device would still be functional when they sorted out the cutter fault. Although he was more than happy to order another there and then, we said we thought it worthwhile to give the existing isolator a try, and never heard from him again!

SCIMAR Engineering Ltd, 39 Marsh Green Road West, Marsh Barton Industrial Estate, EXETER, Devon,EX2 8PN, U.K.

Tel: +44 (UK) (0) 1392 496540

Fax: +44 (UK) (0) 1392 496684