| ??? 12/03/04 01:53 Read: times |
#82441 - RS 485 Contention Responding to: ???'s previous message |
Hi Russell,
Thanks for your reply. I always put an inverter on the enable signal to eliminate the problem. I have made my mind to use an Invertor to avoid contention at startup but using this invertor is using another problem. That is upon using an invertor the /RE will go enabled at startup. I am using P89V51RD2 micro these micros are such that upon power up they try to autobaud ISP signals on their UART if they suceed in receving an 'U' during 400ms since power up they enter ISP mode else execute their program. Now the problem is say I turned on node '3' and at the same time there was an stream of 'U' being send from node '5' to PC node '1'. Node '3' has just started so the micro is trying to autobaud ISP and is waiting for getting an 'U' since due to invertor /RE is enabled this micro will get those 'U' on its UART and enter ISP mode and will it in ISP mode for getting hex records but since there are no hex records being transfered on RS485 bus that micro will wait in ISP untill reset. How to address this problem. Thanks & Regards, Prahlad Purohit |
| 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 |