i use a rs 422 converter with 4 terminal but i could not download hex to card from pc... what is the problem? about converter connection or about flash program? In connection, 1 is T+, 2 is T-, 3 is R- and 4 is R+. And R+ goes to T+. R- goes to T-...... ..and so on as said in datasheet. The converter is in SIM mode...
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what can be the problem??? com port is found by pc, and being connected.. but when pressing download, i get an error like this: "Error during Downloading. Connection is closed"... What is this about?? The program is xc800 fload 4.7 . Thanks...
Assuming that you have properly set the baud, data bits, stop bits, and parity, try swapping the polarity of the T and/or R lines. One side of a data link or the other always seems to get it wrong.
Also, I'm not familiar with the XC800 FLOAD application, so check as well that you don't need to have any handshake lines (DTR, etc.) hooked up to trigger or to pace the hex file load.
Hard to say, since you did not say what switch settings you are using on the converter.
Please note that one manufacturer might call the same signal TX+, while the other calls the same signal TD-
Those are unofficial notations for the RS-422 pins.
The only reliable RS-422 notation is the names used in the actual RS-422 standard. The transmit pair is called A/B and the receive pair is A'/B'. You connect A to A' and B to B'. Do not rely on T+/TD+/D+ unofficial notations, since these vary from vendor to vendor.
Hi, i am using such a simple connection.... I use ADM488 pins (8,7,6,5) whi ch are directly going through converter on board schematic. I think i am d oing sth wrong here... But i cant find what is wrong.... I tried to swap ca bles in different modes but i got same error again. I also put jumpers on d ownloading phase. I cant understand what is problem :(((
what is your full mail adress ? i can send the photo of converter and pin s cheme to yoou.... but i cant see your mail upsid..???????.@downunder.com
31 Ocak 2014 Cuma 21:24:19 UTC+2 tarihinde snipped-for-privacy@downunder.com yazd? ?:
card from pc... what is the problem? about converter connection or about f lash program?
R- goes to T-...... ..and so on as said in datasheet. The converter is in SIM mode...
. but when pressing download, i get an error like this: "Error during Downl oading. Connection is closed"... What is this about?? The program is xc800 fload 4.7 . Thanks...
31 Ocak 2014 Cuma 21:24:19 UTC+2 tarihinde snipped-for-privacy@downunder.com yazd? ?:
card from pc... what is the problem? about converter connection or about f lash program?
R- goes to T-...... ..and so on as said in datasheet. The converter is in SIM mode...
. but when pressing download, i get an error like this: "Error during Downl oading. Connection is closed"... What is this about?? The program is xc800 fload 4.7 . Thanks...
Can you suggest me anything that i am supposed to do on which cable??? You can look at the photos above. I indicated the pin numbers on card schematic . I hope you can help me..and i can understand what to change.. Thanks
1 ?ubat 2014 Cumartesi 02:43:28 UTC+2 tarihinde Nick Leverton yazd? ?:
o card from pc... what is the problem? about converter connection or about flash program?
. R- goes to T-...... ..and so on as said in datasheet. The converter is i n SIM mode...
.. but when pressing download, i get an error like this: "Error during Down loading. Connection is closed"...
You may also need to connect signal ground between the two devices (unless both have signal ground connected to earth ground they are sharing an earth ground).
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Make sure you get the switches right, especially T-ON/R-ON to activate the transmitter.
On the RS-232 check the DCE/DTE switch. On the RS-422/485 side, check that transmitter is always o.
Perform the "loop back test", use e.g. Hyperterminal to type some characters and observe that the characters are echoed on the screen. Remove the jumper and nothing should be echoed. This will test that the converter is working as expected.
Assuming the posted diagram and pin assignments are OK, there are 100 terminator resistors between A/B and A' / B' pairs and assuming 1 V voltage drop in each totem pole transmitter transistor, the voltage swing with a short cable is about +/- 30 mA, so you get a hefty signals across the receiver pins, with definitively are going to provide the receiver with sufficient receiver transistor base bias current, even without a signal ground connection.
The situation might be different if the devices are in different rooms grounded to different earth potentials, but in this case, it is quite unlikely to be the problem.
That's immaterial. The problem with running without a signal ground connection is not the amplitude of the differential signals, it's whether or not the common-mode voltage stays within the spec's for the receiver.
That's only true if signal ground is connected to earth ground in both ends and both ends share earth ground. If you look at the second diagram there are two different grounds shown: the signal ground and "GND-ISO" which is using the earth/chassis ground symbol. That probably means that signal ground is isolated from earth on that end.
When using RS-422 and RS-485 you need to connect signal ground if you want reliable communications. Relying on a shared earth ground to make sure that differential signals are within the common-mode voltage spec of the receiver is the sure mark of an hack, and I've seen it cause countless problems during the 30 years I've been working with RS-422 and RS-485.
It may or may not be a problem. When you don't connect a signal ground, your're always just rolling the dice and hoping for the best.
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