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+--- Thread: HP48 machines as Serial Port Monitors (/thread-11023.html)
HP48 machines as Serial Port Monitors - TomC - 07-08-2018 03:12 PM
Has anybody had any experience with using two HP48s to monitor the TX and RX lines of a serial port?
I've been troubleshooting a RS232 connection to an instrument, and there are many times where I'm guessing as to what is happening on the serial port. It would be helpful to monitor the activity - eg is the instrument sending a stop transmission character etc. This is strictly a simple RX/TX connection with no HW handshaking.
I'm thinking both of these monitor H48s have each of their RX lines connected to the respective RX and TX lines of the instrument/controller port. [I presume impedance loading will not be an issue.]
Of course these monitor machines would be set up with the appropriate baud, party, bits etc...
TomC
RE: HP48 machines as Serial Port Monitors - acoto - 07-08-2018 04:33 PM
It should work. If interface cabling distance/impedance is not too high, it should not affect the communication between external devices.
Just grab a terminal application and try it.
https://www.hpcalc.org/hp48/utils/terminal/
Electrical details here:
https://www.hpcalc.org/hp48/docs/misc/io2.txt
"The serial I/O port allows full-duplex communication between systems at 1200,
2400, 4800, or 9600 baud over wires with RS-232 compatible signal levels.
Available parity settings are: none, odd, even, mark, or space."
RE: HP48 machines as Serial Port Monitors - acoto - 07-08-2018 04:46 PM
If concerned about affecting line impedance, you may add an external voltage follower between RX-TX external line and HP 48 RX.
http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/opampvar2.html