| ??? 08/17/11 08:21 Read: times |
#183382 - GNDs Responding to: ???'s previous message |
Thank you very much for the comprehensive answer... ;)
Kai Klaas said:
This cap can be omitted if you have an output filtering cap connected from the output voltage pin to the output ground pin of DC/DC-converter. OK, there is no filtering cap in my case so I will add one to the output. I have 10uF/16V 1206 available. Kai Klaas said:
These 100R resistors are to deal with hum loops. If your design avoids hum loops, then there's no reason to have them. If you are not sure, at least decrease them to about 10R or so. I just found the datasheet from B&B Electronics (http://sss-mag.com/pdf/485appno.pdf) which I used to design the schematic of RS485 some time ago. I took most of the information from it. There are example figures with 100R resistors between GNDs (page 8) and with transient suppressors (page 17)... I used it in the same way with a small difference - I have only one connection point to Earth GND in the convertor... I am a begginer in RS485 design so I am grateful for any advices and hints ;) Kai Klaas said:
The cap at the DC/DC-converter could serve as this cap. The input ground of DC/DC-converter is connected to PE via the personal computer, isn't it? No, PE of the computer is connected via 100R resistor to the output GND of the DC/DC convertor. And output GND of DC/DC convertor is connected to the signal GND of RS485 via 100R resistor to set the right ground potencial as it is in the B&B datasheet. It is also shown on the shematic I have posted. Regards Lukas |
| Topic | Author | Date |
| Problem with RS232/RS485 converter... | 01/01/70 00:00 | |
| More info please | 01/01/70 00:00 | |
| probably | 01/01/70 00:00 | |
| more info... | 01/01/70 00:00 | |
| yes,i think | 01/01/70 00:00 | |
| input impedance | 01/01/70 00:00 | |
| i'm wrong | 01/01/70 00:00 | |
| what is the right value? | 01/01/70 00:00 | |
| did You tryed capacitor? | 01/01/70 00:00 | |
| thanks... | 01/01/70 00:00 | |
| it works...! | 01/01/70 00:00 | |
| congrats | 01/01/70 00:00 | |
| shape | 01/01/70 00:00 | |
| dont | 01/01/70 00:00 | |
| It is OK. | 01/01/70 00:00 | |
| Hints... | 01/01/70 00:00 | |
| schema | 01/01/70 00:00 | |
| Repair... | 01/01/70 00:00 | |
| transils... | 01/01/70 00:00 | |
| RS485 | 01/01/70 00:00 | |
| Sample Schematic | 01/01/70 00:00 | |
| Thank you very much for the schema... | 01/01/70 00:00 | |
| AVX varistors... | 01/01/70 00:00 | |
| capacitor | 01/01/70 00:00 | |
| capacitors... | 01/01/70 00:00 | |
| GNDs | 01/01/70 00:00 | |
| 1992 | 01/01/70 00:00 | |
| Thanks... | 01/01/70 00:00 | |
Links... | 01/01/70 00:00 |