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No worries. At this point I am happy to be questioned on anything The link is terminated correctly. The baud rate I'm using is 115.2kbaud. Just to clarify, for debugging purposes and to try to understand the Modbus errors, I'm not even connected to a slave device right now. I'm just transmitting to a terminal app on a PC. I have not seen any communication errors at all - by no errors I mean no bit or byte errors. All commands that are transmitted are received at the terminal properly formatted and with correct CRC. The issue appears to be when the Modbus Master determines there is an error (either because there is no response or because the next transmission happened too quickly before the previous one has timed out - within 500ms). So , it's not so much a comms issue, but more a protocol issue I'm dealing with. I've been discussing with Unitronics support, but I have to question their responses. They are claiming that the only time there is a 3 second suspension by the Master, is when a transaction generates a -2 error code. However, when I try to send three transactions in a row, with a 1 second delay between each, it does not work. The first command times out (as expected since I am not trying to respond) and generates an error code -11 as expected. However, the second command does not transmit at all and generates an error code -2 even after waiting a full second. Since the 1 second delay between 1st and 2nd commands was not enough, this leads me to believe that the -11 timeout error also caused this 3 second suspension in the first command. If I increase the inter-command delay to 3.5 seconds it works, which again leads me to believe the 3 second suspension is being generated by the timeout even though Unitronics support says it does not. I know from the documentation that the -2 error does cause the 3 second suspension (maybe others too), but what they have been unable to tell me is what actually causes a -2 error to occur? What is the condition that generates it? -
I'm addicted to drinking brake fluid, but I can stop whenever I want. What is Forrest Gump's password? 1Forrest1. (Still here? ok...here's more...) I have a side job making plastic Draculas. There are only 2 of us doing it, so I have to make every second count. What do you call a pony with a cough? A little horse. (Ok, you can go arrgghhhhh now! But there will be more...... 😉) cheers, Aus -
I've been squizzing at the specs for that module, and a question is what baud rate are you using? Does changing the rate change the timings you're experiencing? Start low and speed up for the tests. And questions which might sound insulting, given it sounds like you know what you are doing..... Are the correct resistors in the correct place, and/or the unit's termination set correctly? Is the cable a quality one? cheers, Aus
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Okay, I'll give it a try. Thanks for the find! -
By Joe Tauser · Posted
There is not. There are quite a few functions in Vision that don't exist in UniStream. PWM and Linearize Array immediately come to mind. The thing about a function in Vision is you don't know what the assembly code looks like under the hood to get that function to work. We got spoiled by some of that stuff. Here's the RTC to ASCII udfb I lifted from the example programs. Looking through it gives us an indicator of what kind of somersaults the Vision programmers performed for that function. You can call it overkill if you wish. But it does work. Joe T. RTC to ASCII V2.ulle
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