USB to Serial Port cable for 41CL

[Monte Dalrymple]

(08-28-2016 05:31 AM)mfleming Wrote:  On my 41CL I have the serial port accessory for the 41CL and the DB9 to audio plug cable provided for the port cover receptacle. I picked up a Sabrent adapter cable at Frys long ago to communicate with an HP48 via its DB9 serial port adapter cable; works just fine. A quick check of the DB9 pins shows about 6.5V on some of them (scary!). The 41CL manual mentions an RS232 transceiver, and the schematics show a part with such a label but alas no part number to look up the data sheet. Having used USB to 3.3/5V serial port adapters for Arduino type targets, I want to be sure I'm not applying an inappropriate voltage to the 41CL board.

The 41CL serial port is RS232. That means the standard voltage levels.
The driver is a Maxim MAX3221.