Keithley 2231A-30-3 Communication - Page 1
Forum section: electronics / testgear

author: simba15
author_rank: Regular Contributor
timestamp: October 18, 2021, 03:49:49 pm
content: Hi there,I am working with a large number of the Keithley 2231A-30-3.I would like to communicate with it VIA PC but Tek, states you must use the Keithley USB adapter ($$$)I have found the pin-out of the propriety connector (2=rx,3=tX).Has any one been able to get this power supply to communicate to their pc? ( may only respond to read only commands)Thanks.

author: simba15
author_rank: Regular Contributor
timestamp: January 11, 2022, 02:30:35 pm
content: So I connected a FTDI TTL adapter tx/rx and tried with EEZ studio to get a response for a *IDN? command.I cant get a response in the software but i can see that both Tx/Rx lights illuminate. (there is a response of some kind.)Any ideas where the issue could be?I will try with "Test controller" software.

author: alm
author_rank: Super Contributor
timestamp: January 11, 2022, 02:35:30 pm
content: Did you try different baud rates / flow control / parity / stop bit configurations? If it outputs anything on power on, you could capture that with a scope or logic analyzer and check the repetition rate and count the number of bits.

author: simba15
author_rank: Regular Contributor
timestamp: January 11, 2022, 02:48:50 pm
content: Quote from: alm on January 11, 2022, 02:35:30 pmSo the Manual Lists the Baud rate and flow settings 9600,8,N,1 ( this is what the program is set for)If i use a incorrect baud rate 57600 or other, the RX light dose not illuminate.I will try and scope the RX Line.

author: BennoG
author_rank: Frequent Contributor
timestamp: February 19, 2024, 06:24:58 am
content: was you been able to communicate with the device ?It uses 3.3V level RS232 signals at 9600 baud.I found it to be very slow for the measurements of the output Voltage and Current (300+ ms per query)Have you come around this problem ?Benno

author: simba15
author_rank: Regular Contributor
timestamp: April 23, 2024, 03:24:17 pm
content: interesting!I probably fried it with standard RS232 levels as it stopped responding at some point. ( duh... it says (TTL) lol)I have 10 or so of them so I may try again with 3.3v levels.Thanks.

author: BennoG
author_rank: Frequent Contributor
timestamp: April 23, 2024, 03:48:35 pm
content: Be also aware that the RS232 output uses the same ground level as CH3 output.So I put also a isolator in the USB-RS232 converter (there is 5V on the 9 pin sub-D to supply the psu part of the logic)P.S. I figured a way around the slow communication, see my other post in on the 2231A, including C# source code and a nice HMI you can use to click on.Benno

author: Smokey
author_rank: Super Contributor
timestamp: March 27, 2025, 07:17:41 am
content: wow. I was just looking at one of these supplies online. what a crazy decision to include a DSub and force your users to buy a $97USD USB adapter. Seriously what the hell were they thinking?This design doesn't much look like other Keithley stuff, so I'm guessing it's a rebadge or something. But still.https://www.mouser.com/ProductDetail/Keithley-Instruments-Inc/2231A-001?qs=DWa7j9kREiEoYVPT6mrqPg%3D%3Dhttps://www.mouser.com/datasheet/2/403/077101500_USBadapter_8-3358684.pdfhttps://download.tek.com/datasheet/2231A-30-3_Datasheet_1KW-61078-0.pdfQuoteSo it's not like they expect you to directly use the DSub, and the USB cable is optional or something.

author: chilternview
author_rank: Frequent Contributor
timestamp: March 27, 2025, 11:04:08 am
content: I guess a bean counter objected to having a MAX232 in there to convert to proper RS232 levels, "oh it will cost $1"...Still rather than pay for the adapter you could make one with said chip and a little effort. The 2231A is a good power supply, I use mine all the time.

author: BennoG
author_rank: Frequent Contributor
timestamp: March 27, 2025, 11:41:12 am
content: Too bad the communication can nog go above 38400 baud. But I use it also al the time with a home made isolated TTL232 to USB converter.So the 5V output is also isolated from the ground of the PC.Benno

author: htrueba
author_rank: Newbie
timestamp: July 29, 2025, 07:25:14 pm
content: I managed to get communication working without their connector. All I had to do was get an FTDI TTL converter (https://www.amazon.com/NITOMTYU-Serial-Adapter-TTL-232R-RPI-Windows/dp/B0CFV96CDD/) and a DB9 breakout connector (https://www.amazon.com/Breakout-Connector-RS232-Serial-Terminal/dp/B073RGFD3Q/).The links were just to example items but I'm sure they can be found for cheaper somewhere else.Just connect RX, TX, and GND on the ttl cable to TX, RX, and GND on the DB9 breakout board . If it doesn't work immediately, swap RX and TX.Hope this helps someone else!