LDM85 - Serial to Fibre Optic Modem

Extended Wide Temperature

These products utilise high quality industrial grade components enabling them to work in extended wide temperature environments. They are capable of running below -20C and above +70C and offer further protection than standard wide temperature rated products.


This product fully adheres to the Restriction of Hazardous Substances Directive 2002/95/EC, RoHS for short.  The directive covers the restriction of use of certain hazardous substances in electrical and electronic equipment and was adopted in February 2003 by the European Union.


CE is a mandatory standard for products on the market in the European Economic Area. By CE marking a product, the manufacturer ensures that the item meets the essential safety requirements set out in the applicable CE directive.

LDM85 Serial to Fibre Optic Modem
Featured in:Dataforth Communications
4 LDM85 versions available
Free delivery to UK mainland addresses

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LDM85 with female DB25 connector and SMA (905) fibre optic connector
1 in stock
LDM85 with male DB25 connector and SMA (905) fibre optic connector
LDM85 with male DB25 connector and ST fibre optic connector
LDM85 with female DB25 connector and ST fibre optic connector
Peripheral information
Lead time*
1 off price**
Request Qty Pricing**
Buy now
12V AC UK Power Supply
2 in stock
12V AC US Power Supply
12V AC European Power Supply
All prices exclude VAT at current rate.
Minimum order value - £30 (exc. VAT and delivery).
Free delivery of the LDM85 to UK Mainland on orders over £150 (exc. VAT and delivery) when purchasing online - excludes Northern Ireland, Isle of Man, Isle of Wight, Scottish Islands and the Channel Islands.

* Lead time is indicative and is subject to change at time of ordering. Next business day delivery on in-stock products only (when ordered before 3pm).
** Contact us for quantity or project pricing.
† Additional delivery charge may be incurred for certain postcodes (calculated at checkout)
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LDM85 overview

  • Industry leading industrial fibre optic modem
  • Data rates to 5M baud
  • RS-232, RS-422, TTL system interfaces
  • Multipoint capability
  • LED status indicators
  • DCE/DTE switch
  • Small size & low cost
  • SMA- or ST-compatible optic connectors
  • 120/220V AC, +5V DC or 8 to 20V AC/DC power
  • Available with a pinned male DB25 connector (LDM85-P) or a socketed female DB25 connector (LDM85-S)
The LDM85 is a small, inexpensive fibre optic transmitter/receiver. It features a complete RS-232/422/423 port as well as high speed TTL data transmit and receive. It is capable of data rates from DC to 5M baud. A pair of these units allows most RS-232C cable links to be replaced and extended with a duplex fibre optic cable. The normal 50-foot RS-232 limit may be extended to 1.2 miles (2 km). Fibre optic data communications provide complete EMI/RFI rejection, isolation, elimination of ground loops, and reduced error rates. Data security is enhanced by almost nonexistent electromagnetic emissions. A unique multipoint capability allows local area networks to be formed with the isolation and data security of a fibre optic data highway.

The LDM85 is packaged in a rugged aluminum enclosure small enough to mount on the back panel of typical computer equipment, saving valuable desk and floor space. The RS-232 connection is through male or female EIA 25-pin connectors. The fibre optic connection is either through SMA (905) or ST connectors. Additional features include a TD/RD reversing switch for connection to DTE (Data Terminal Equipment) or DCE (Data Communication Equipment) ports, three diagnostic LED indicators, and locally connected handshake lines. The TTL port combined with the RS-232 port may be interfaced to RS-422/423 ports in 4-wire point-to-point mode only.

Fibre optic cables may be ordered with connectors factory installed.
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