I am wondering if the RS-232 to RS-485 Converter, SKU: TEL0038 will work with 19200 Bd, 7, E, 1 serial parameters, half duplex, transparently two ways, protocol independent.
Thanks, Darko.
Hi Darko,
From what I’m reading in the product details, this should be compatible for that application!
Thank you, Stephen. Does it mention specifically 7 and 8 bit? I have a bad experience with those cheap products whereby they do not specify much, but the built-in chip does not support the 7 bit data word. For me this is crucial as I want to talk to a Hitachi PLC by the H protocol which is exclusively 7, E, 1.
If your device can be tested with these parameters that would be great. I tested one cheap one using two USB converters, Modscan and Modsim. 8,x,x worked ok, 7,x,x did not.
If that’s stretching the friendship, but if you are reasonably sure it will work I’ll buy it and see how I go. I just don’t want to end up with too many paper weights.
Regards,
Darko Grujic
0400221225
Hi Darko,
I cannot promise that this device will be capable of 7-bit data words, and unfortunately do not have a method of testing to see that it might be capable. I found a simple data sheet for this device on the manufacturer’s website and it made no mention of that capability.
Ok, thanks kindly for your time, Stephen.
Regards,
Darko Grujic
0400221225
If the device in question is just a simple RS232 to RS485 receiver/transmitter then the number of bits, parity, stop bits, etc is irrelevant. These are a function of the UART, which this device would be connected to. I would not expect something like this device to have a UART built in. But I could be wrong. The manufacturers datasheets for the type of ICs that would be in a device like this, do not specify number of bits. Because the device simply reproduces what is sees on side to the other side.
Anyway, my 2 cents for the day.
Jim
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Thanks for the input James. I wasn’t aware of that about the 7-bit 8-bit thing!
Thanks, James. When the manufacturer specifies just the Baud rate and no other serial parameters, you’d expect that everything else is there and the device is totally transparent.
Unfortunately, in my experience, this hasn’t been the case and when I queried it I was told that this 7 bit word is special, requiring a special chip. 7 bit word is, of course, not special, but the cost of the chip is probably higher which ends up with a misleading situation.
Thanks for your time and your advice.
Regards,
Darko Grujic
0400221225
With serial communications the bits are sent one after another with a start and stop bit they are both Asynchronous Serial protocol so the bit of each character should be negotiated at the beginning of transmission and not really anything to do with the actual transmission so the converter should just work. Unless the Hitachi PLC is doing something else funny like using 7bits for data and 1 for parity but still sending with 8.
That’s correct, Clinton. However, I’m not familiar with the details of H protocol, so I can’t say. On, the other hand, both USB to RS232 and USB to RS485 converters work with no problems, although there were cases a while ago where there were problems with some USB to RS232 converters.
Thanks.
Regards,
Darko Grujic
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