| ??? 12/02/04 23:48 Read: times |
#82439 - RS485 contention Responding to: ???'s previous message |
Whilst I have no input on the issue of IAP, the issue of the 485 driver being enabled on startup is something that needs to be addressed. I always put an inverter on the enable signal to eliminate the problem. In terms of protection of the 485 driver, I use 5V tranzorbs and 300mA polyswitches. The polyswitches are used to protect the transzorbs as they like to go up in smoke if you put 24vdc (in my application - likely) on the rs485. With this combination, the 485 driver and the protection circuit survives the application of 24vdc as well as the industrial immunity tests for CE. For your RS485 interface to the PC, I would recommend the Advantech ADAM 4561? USB->RS422/485 interface. This interface takes care of the driver enable in hardware so your software does not even need to know about RS485 (apart from being half duplex). If you send data, it knows to enable the tx, when finished, it disables the tx. In Australia, they're about AUD$160. Not super cheap, but they do the job well. Plug in, load driver, run your code - job done - instant RS485. |
| Topic | Author | Date |
| RS485 Contention. | 01/01/70 00:00 | |
| 485 ISP | 01/01/70 00:00 | |
| RS485 'U' & ISP | 01/01/70 00:00 | |
| the crux | 01/01/70 00:00 | |
| Flashmagic !!!! | 01/01/70 00:00 | |
| RS485 contention | 01/01/70 00:00 | |
| Cygnal F12x | 01/01/70 00:00 | |
| Reply to Erik | 01/01/70 00:00 | |
| FM< half duplex | 01/01/70 00:00 | |
| Reply to Erik | 01/01/70 00:00 | |
| bus direction | 01/01/70 00:00 | |
| A few comments | 01/01/70 00:00 | |
| comnments on comments | 01/01/70 00:00 | |
| comments^3 | 01/01/70 00:00 | |
| boot NIT | 01/01/70 00:00 | |
An example worth 3E8h words :-) | 01/01/70 00:00 | |
| A fundamental query - Erik | 01/01/70 00:00 | |
| testing | 01/01/70 00:00 | |
| RS 485 Contention | 01/01/70 00:00 | |
| RS485 Contention | 01/01/70 00:00 | |
| Switch ? | 01/01/70 00:00 | |
| RS485 contention | 01/01/70 00:00 | |
| Possible solutions. | 01/01/70 00:00 | |
| Thanks Erik. | 01/01/70 00:00 | |
| SOLUTION | 01/01/70 00:00 | |
| Thanks but thats not the solution | 01/01/70 00:00 |