Successfully transfering files between 48SX and 50G

[berserkerbernhard]

Hi all.

This week I successfully transfered text strings between a 48SX and a 50G. Both calculators was connected to a PC through a RS232 (48SX) and USB (50G). The PC was set to bridge both connections.

It actually worked. A text string was send with XMIT and recieved on the other calculator. It's a fully functional bidirectional connection.

My plan is to use a smaller computer like a Raspberry Pi or even an Arduino if the right library exist for it.

It's been a while since I did some serious programming on those calculators, so I'm a bit rusty. I want to write some sort of a client to transfer whole directories over the serial link. That way I can more easily live without Windows and just rely on my calculators.

Please comment below on your thoughts and ideas.

Thanks in advance.

Bernhard/OZ9WTN

[BruceH]

The 'other' socket on the 50G (labeled '0101') is an RS232 serial connector. If you can find the cable for it then you can transfer direct from 48 to 50. (The 50G should have come with one for 50G to 50G comms - you could cut off one end and wire on a 48SX plug. But probably better to find a calc to 'standard' RS 232 plug for each calc and then couple those rather than cut things up.)

PS: There is no need to write a program capable of transferring whole directories as there is one already built in! The 50G has Kermit and Xmodem, both of which can run in server mode (where they sit and wait to be asked to send or receive variables). The 48SX may only have Kermit as a server - can't remember off the top of my head - but it can use Xmodem to send/receive variables manually.

[SammysHP]

Is the output of the 50G really RS232 (inverted and +/- voltage) or just TTL (not inverted and only positive)?

[Steve Simpkin]

(11-30-2018 10:04 PM)SammysHP Wrote:  Is the output of the 50G really RS232 (inverted and +/- voltage) or just TTL (not inverted and only positive)?

I don't know for sure about the RS232 levels on the HP50G. The HP-48SX puts out approximately +/-3 Volts on its RS232 output so I *suspect* the HP50G must do something similar to be compatible with other RS232 computers and devices.

[John Keith]

Actually the HP50's serial port is TTL level, not "proper" RS-232 so some sort of level shifting would be needed. Surely someone must have done this before(?)

[Steve Simpkin]

(11-30-2018 11:11 PM)John Keith Wrote:  Actually the HP50's serial port is TTL level, not "proper" RS-232 so some sort of level shifting would be needed. Surely someone must have done this before(?)

Thank you for the clarification. I found the following information on RS232 conversion cables for the HP50G.
https://www.allenwan.com/hpcalcserialcable/
https://commerce.hpcalc.org/serialcable.php