EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: dmg0345 on June 16, 2021, 04:15:53 pm
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Hi everyone,
The IPS-405 and related are quite popular power supplies and I was hoping someone could help me find a cable to properly connect to this power supply through the RS232 interface from a USB port in my computer.
I have an ISOTECH IPS-405 Power Supply like this one: https://www.enrgtech.co.uk/buy/product/ET13984959/IPS-405. (https://www.enrgtech.co.uk/buy/product/ET13984959/IPS-405.)
I am familiar with serial ports, UARTs, COM ports and the like however I am struggling to find a RS232 to USB for this PSU, from the manual:
(https://i.ibb.co/2nsbfzv/Captura.png)
And this is the connector on the back of the PSU:
(https://i.ibb.co/kqRWtQx/Captura.png)
I find it quite atypical and non standard, this is neither a straight through cable nor a null modem cable, and I am confused as to why I need 12V on that pin, and not anything between 5V and 15V as defined in the RS232 spec for a high level, I have read that some old devices only worked with 12V and rejected any other voltage, I suspect the RXD and TXD pins might work with this voltage too.
Has anyone with a similar PSU recommend any RS232 to USB cable for this board? It does look like I need a custom one, but I hardly believe that this was the expected use case by the manufacturers of this PSU, I am probably missing something.
Thank you for your time.
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Guess about the 12v.
It powers an opto isolation thingy in the PSU , so your computer & psu are isolated from each other.
/Bingo
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Guess about the 12v.
It powers an opto isolation thingy in the PSU , so your computer & psu are isolated from each other.
/Bingo
You are probably right, I came across what seems to be the schematics of this PSU (or a very similar model) and noticed the following:
(https://i.ibb.co/tBvZBcQ/Captura.png)
I thought the 12V signal was DCD, but looking at the schematics it does not look like that, it does something with the optocouples there.
So I guess this provides some clarity, but I still wonder what kind of wire where the original manufacturers expected people to use because I can't find any and I would rather avoid doing something custom.
EDIT: Forum seems to be resizing the image, the image can be seen here: https://ibb.co/NxJ1xpt
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I also looked at the datasheet of the Winbond UC with the TXD/RXD signals, and noticed that the ranges of Input/Output for the TXD and RXD signals are in the range of 0V to 5V it seems: https://ibb.co/n3Ybpfq.
So it looks like a 12V input, a normal UART and a RS232 connector.