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Forum Index : Microcontroller and PC projects : [MicroMite] How is RS485 implemented
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MicroBlocks Guru  Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Can someone tell me how to use the RS485 capabilities of the MicroMite (MMBasic). What kind of setup can be made. One master/multiple slaves, multiple masters/multiple slsaves? Is there a provision for bus conflicts? How do two nodes talk to each other? The project i would need it for is for a friend who has a catamaran with two diesel engines that need to be controlled. Each engine would get a uMite for measuring RPM, temperature and oil pressure. It would also control gearing (forward/idle/reverse) and throttle by using dc motors and using switches as feedback for the gearing and measuring RPM and end switches for feedback on the throttle. the uMite should be able to transmit all measurements on a interval of about 5 seconds with faster intervals when throttle is used. It should also be able to receive commands for choosing gear and RPM. Main concern is reliability. I understand that with RS485 you need to build reliability using a good protocol. Is there already a lower level protocol built in the firmware upon which i can put another 'data' layer? Thanks! Microblocks. Build with logic. |
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CircuitGizmos Guru Joined: 08/09/2011 Location: United StatesPosts: 1421 |
If you are not using a protocol like MODBUS, you can roll your own. Look at the protocol called S.N.A.P. http://www.hth.com/snap/ You can implement S.N.A.P. or at least use it as a guide to making your own protocol. I typically use a master/slave/slave topology with the master polling at the rate it chooses. Slaves are addressable. Micromites and Maximites! - Beginning Maximite |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Thanks CG. That looks like a good and easy protocol to use. Microblocks. Build with logic. |
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