8431/8 schematic

[Leon_Black]

Hello,

I work for ABB Inc out of Bartlesville Oklahoma. From time to time we have issues with the 8431/8 operating at 9600, no parity, 8 bits and 1 or 2 stop bits.  I think the issue comes in 3 parts and I will try to ask the questions in terms of issue priority.

Bus Turn Around time when running as half duplex in 2 wire automode. How soon after the last byte leaves the UART does the processor turn the transciever from transmitt mode to recieve mode. Is the input buffer available immediately on turn around or is there a built in delay?

I see from data on the PCIe-8431/8 422/485 that the biasing resistors are not the PCBA with no options to put them in the cable. This last part is an assumption based on what I can find on the 68 pin header. No positive supply voltage, no way to bias the individual ports. This means the we as users have to find a way to bias the ports to meet the requirement of "all biasing and termination resistor must be in place" ( taken from Ni literature on serial interfaces). Because of this I am asking if a schematic exists for the PCBA assembly and does NI offer a recomended procedure for placing the resistors on board?

I see that NI offers the termination resistor pass through module and I guess that works for assemblies that have only two ports but how does the termination work without the biasing resistors?

[WestOfEden]

I don't know offhand but will start to take a look into this to see what I can fiind. However since you have some pretty in depth questions it might be faster to create a service request (if you have a support package) and working with an applications engineer that way. 

[WestOfEden]

So all I was able to find in regards to the biasing was a KB which at the bottom states "the PCIe-8431\8\16 does not have built-in biasing options. Instructions for biasing can be found in the Serial Troubleshooting Wizard. Please remember that all specified biasing and termination resistors are required.". 

Here is a link to the Serial Troubleshooting Wizard it mentions:

Serial Troubleshooting Wizard

http://www.ni.com/support/serial/resinfo.htm

For the other two questions, I haven't yet been able to find an answer. I would recommend creating a service request at ni.com/support if you have standard support, and reaching out to our support team that way. 

[Leon_Black]

I will try the service request. Thanks for the help so far...

[runningtree]

Hi Leon_Black .

I have also met the same question as you. Have you got the answer in the end? I hope it can be published here for everyone's reference.Looking forward to your reply.