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ntrungtruc2003
Joined: 16 Feb 2011
Posts: 42
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| explain holding register for modbus slave 16f877a |
 Posted: Sun Dec 25, 2016 12:30 am |
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Dear Sir
I successfully tested a modbus slave for 16f877a with Kepserver.
But I do not understand the address of registers:
| Code: | the int16 hold_regs[] = {0x8800,0x7700,0x6600,0x5500,0x4400,0x3300,0x2200,0x1100};
int16 input_regs[] = {0x1100,0x2200,0x3300,0x4400,0x5500,0x6600,0x7700,0x8800}; |
holding registers for modbus are 16 bits from 40001---49999.
The address 0x8800,0x7700,0x6600,0x5500,0x4400,0x3300,0x2200,0x1100
Where can i find the register 0x8800, 0x7700,... on 16f877a manual ?
What standard declare holding register address on 16f877a ?
Thank you very much. |
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temtronic
Joined: 01 Jul 2010
Posts: 9162
Location: Greensville,Ontario
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| Posted: Sun Dec 25, 2016 5:57 am |
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re:
Where can i find the register 0x8800, 0x7700,... on 16f877a manual ?
You can't, those registers are for MODbus not a PIC. You should get a book on MODbus to understand MODbus.
While I don't use MODbus, it's just another form of communcations, like RS485, PPP, I2C,SPI or MSC500 that have clearly defined standards and protocol. The PIC 'driver' or program simply allows you to use a PIC to communicate with a MODbus device.
Jay |
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