Purpose
Create a cable that will directly interface Optoelectronics Digital Scout "Reaction Tune" port to a USB port. This cable will provide frequency counter hits only (transmit).
Important Note: the RS232 port on the Digital Scout does not transmit/receive at TTL levels and should not be connected to the TTL -> USB adaptor described here. If you wish to have both transmit and receive than a RS232 -> USB adaptor should be used.
Alternate Approach
The RS232 port on the Digital Scout provides for both frequency counter -> PC as well as PC -> frequency counter communications. This port should be modifiable to provide TTL transmit/receive or an new port could be added to the Digital Scout. More information on TTL transmit/receive out of Digital Scout.
Pin Mapping
References
Digital Scout Serial Interface Specification:
http://www.optoelectronics.com/tech_doc.htm
232R-3V3-WE Data Sheet:
http://www.ftdichip.com/Documents/DataSheets/Modules/DS_TTL-232R_CABLES_V201.pdf