Casio Serial Cables

What different types of cables are there?

Order a cable

Build your own cable

Which cables are compatible with XLink/Win and CASIF/Win?
(short answer: All)

FAQ about Casio digital diary communications

This page is maintained by IMSL Software
Updated Sep 14, 2015

Basic Information

Most Casio digital diary models have a small serial port on the side where you can connect a serial cable to exchange data with a PC (or Mac or whatever). The serial port accepts either a 2.5mm plug or a 3.5mm plug, depending on which model you have. Do not try to adapt one plug size to the other - the 2.5mm port operates at 6 volts, while the 3.5mm port operates at 12 volts. Do not try to wire your PC serial port directly to the diary port without the proper cable electronics - this will damage your diary. Do not experiment with cables intended for other devices which happen to have a similar 2.5mm plug! There is no standard, and most of these cables are wired differently from the Casio diary cable. Not only will they not work, they might damage your diary. If in doubt, send us a message and ask.

The PC end of the cable is a standard 9 or 25-pin serial connector (or a Mac serial DIN connector) to connect to a COM port. Your PC must have a free COM port to allow connection to the Casio diary. No other type of port will do. If you have a new computer with only a USB port, then you must buy a USB-serial adaptor (see below for mail-order sources).

You can buy a Casio serial cable separately and use it with XLink/Win or CASIF/Win software. It is also possible to build your own PC (or Mac) serial cable using the schematics you can find here.

You can also connect one Casio diary directly to another with a 2.5mm-to-2.5mm cable or 3.5mm-to-3.5mm SB-type cable, but you can't make a 2.5mm-to-3.5mm direct connection since the voltage (and communications protocol) would be incompatible.

If you have a new computer which has no serial ports, only USB, you can use a USB-to-serial converter.

What are the different types of Casio cables?

2.5mm cable

All Casio diary models up to the SF-5x90SY series used the same 2.5mm serial port operating at 6 volts. The port accepts a 2.5mm mini-stereo plug with 3 contacts. This port design is also shared by Casio FX calculators and Casio QV digital cameras. A voltage adapter is required in the cable to convert between 6 volts at the diary end and the 12 volts used by most standard serial ports on PCs, Macs, and other serial devices (the RS-232C minimum standard is actually 7.5 volts).

The voltage adapter electronics in the cable require external power, which may be drawn from the RTS and/or DTR pins on the serial port at the PC end, or supplied by a separate battery. The original Casio FA-100 interface was a separate box containing the electronics powered by 4 AA batteries. Travelling Software introduced the first cable to use embedded electronics powered from the serial port with no need for batteries, and this design has been used by most subsequent cables. However, there are two small problems with this design:

  1. Serial ports were not intended to supply power to external electronics, and not all serial ports are able to supply enough current. Only the two pins RTS and DTR are available to supply power (at least on 9-pin connectors) and both of them together are usually required to supply enough current. Even that may not be sufficient with some serial ports, in which case a separate battery may be required to achieve reliable operation.
  2. The settings of RTS and DTR to supply the correct voltage are non-standard, and different cable designs require different settings. Software designed to work with one cable may not work with another cable because of this.

Some cables use a single chip voltage adapter such as the MAX-233, while others use discrete components (see the links on this page for the different designs). All four possible combinations of settings for RTS and DTR have been used in different cable designs, so be sure to verify which settings your cable requires. The most common setting (used by the PC-Link cable and the Casio FA-127/128 cables) is:

3.5mm cable

Casio diary models in the SF-5x90SY, SF-6x00SY, and SF-7x00SY series use the 3.5mm serial port operating at 12 volts. The port accepts a 3.5mm stereo plug, the same type used by portable stereo headphones. In this case no voltage adapter is needed in the cable, but some electronic components are still required to provide current limiting and protection. All of these cables require the following settings for RTS and DTR:

Direct diary-to-diary cables

Casio digital diaries are capable of communicating with each other directly using a 2.5mm-to-2.5mm or 3.5mm-to-3.5mm cable. Casio sells the SB-60/62 cable for this type of connection. No electronic components are required in the cable in this case, and the two ports are wired directly to each other. Obviously you can't mix the two plug sizes because you would be connecting two diary ports operating at different voltages.

Build Your Own Cable

You can build your own cable fairly easily for less than $20 worth of parts. The electronic components are often just a single chip or a few discrete components housed in the connector cover. The older Casio diaries (the ones that use the smaller 2.5mm plug) require a voltage step-down circuit in the cable. The newer models that use a standard 3.5mm plug do not.

The 3.5mm cable requires fewer components, and is therefore easier to build. Specifications for the 3.5mm cable are available from IMSL Software if you want to build your own.

You can find the schematics for the original Casio 2.5 mm cable built with discrete components at Larry Berg was the originator of this patented design used by many handheld devices, and he always made it freely available to individuals, so remember to say a word of thanks to him when you use it.

Here is a set of cable diagrams for the a 2.5mm cable using the MAX232 or MAX233 voltage adapter chips instead of discrete components, courtesy of Lee Mckenna.

The following very nice UK web site has the most complete set of instructions and alternative circuit diagrams for constructing your own PC-BOSS serial cable: Gareth Blades Casio web page (link updated March 2013).

You can now buy a ready-made USB-serial cable that includes the voltage step-down circuit needed for the older Casio models: FTDI - TTL-232R-WE - CABLE, USB-TTL SER CONV 5V, WIRE END. Needs only the 2.5mm plug to be added to connect your Casio diary to a USB port.

If you want to build the SB-60/62 cable to connect one diary to another directly, any of the above circuit diagrams will show you the correct connection of the 2.5mm plug - just remember to cross over the Send and Receive leads between the two ends so that the two diaries will talk to each other.

Mail Order a Pre-Built Cable

If you want to mail order a cable to use with XLink/Win or CASIF/Win instead of building your own, try the following sources: 

PC Cables web page (Currently out of stock)

DCables web page (Currently out of stock)

 PC-Link 9600 web page (em PortuguÍs) * Authorized CASIF/Win OEM *  (Email Antonio Amaro F. Ramos (SP Brasil)

Util'Pocket web page * Authorized CASIF/Win OEM * (Email Util'Pocket (France) )

Any of the suppliers above will ship cables anywhere in the world. Be sure to specify what model of diary you have when you contact them.

Windows Link Inc.   RETIRED (try for support - they bought Windows Link)

Milan Urosevic (Germany) / Milan Urosevic's web page RETIRED (support only) * Authorized CASIF/Win OEM *

Denis Rouleau (Quebec, Canada) RETIRED (support only) * Authorized CASIF/Win OEM *

You can also try the following regional suppliers:

Igor Makarov (Russian Federation) Igor Makarov's web page (in Russian)

The professional cable suppliers marked above as authorized CASIF/Win OEMs can include a registered OEM version of CASIF/Win with their cables.
Some of the other small scale cable builders who are not authorized OEMs might include a copy of the old shareware version of CASIF/Win with their cable, but in that case please note that payment for the shareware version of CASIF/Win is NOT included in the price of the cable. Their shareware copy will also be out of date. In general you will get a better deal on a cable + up-to-date software package from an authorized OEM.

These suppliers at one time carried original Casio cables and other accessories for Casio Digital Diaries, but are probably all out of stock now: 

Global Products Inc.
2221 Hammond Drive
Schaumburg, IL 60173
800-633-0633 or 847-397-4944 (IL) Nationwide
Fax: 847-397-7114


EAI (Eric Armin Inc.)
P.O. Box 644
Franklin Lakes, NJ 07417 (NY)
800-272-0272 or 201-891-9466 (NJ)
Fax: 201-891-5689

Which cables are compatible with XLink/Win and CASIF/Win?

XLink/Win and CASIF/Win allow RTS and DTR to be set independently to support all known Casio serial cables, including:

and the various published build-it-yourself designs.

Cables used with the Casio QV digital cameras and FX-series calculators are also compatible.
Cables used with Sharp organizers, Oregon Scientific organizers, and Olympus digital cameras appear similar but are not compatible.

See the Help file for information on which settings of RTS and DTR to use if the default program settings don't work with your cable. There is also some information on cable settings in the FAQ.

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