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Communication Control Block elements

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Communication Control Block elements

This is a legacy method of configuring the serial port.  Use Open_Serial instead.

However, "under the hood" Open_Serial actually creates a CCB.  A CCB takes this form (this is an example for a MODBUS slave):


;(in your code)
   aCOMSetCCB     COM485,MBpSlaveCCB                  ;start modbus
   ;..other code ..


   ;NVEM0 data
   NVEM0

MBpSlaveCCB
   NV0Byte  1                                         ; 0  protocol, 1 = MODBUS slave
   NV0Byte  0                                         ; 1  device address (will be set by the ComDevAddr instruction)
   NV0Byte  0                                         ; 2  comms profile 8,n,1
   NV0Byte  5                                         ; 3  5 = 9600
   NV0Byte  0                                         ; 4  ** not used **
   NV0Byte  0                                         ; 5  ** not used **
   NV0Byte  0                                         ; 6  ** not used **
   NV0Byte  0                                         ; 7  ** not used **
   NV0Byte  0                                         ; 8  ** not used **
   NV0Byte  0                                         ; 9  inter message gap
   NV0Byte  0                                         ; 10 message timeout time
   NV0Byte  0                                         ; 11 retry count (unused)
   NV0Byte  0                                         ; 12 Permitted RAM write start address
   NV0Byte  0                                         ; 13 Permitted RAM write end address (both = 0 all permitted, both = 255 none permitted)
   NV0Byte  255                                       ; 14 Permitted OUTPUT write start number
   NV0Byte  255                                       ; 15 Permitted OUTPUT write end number (both = 0 all permitted, both = 255 none permitted)
   NV0Byte  0                                         ; 16 ** not used **
   NV0Byte  0                                         ; 17 ** not used **
   NV0Byte  0                                         ; 18 ** not used **
   NV0Byte  0                                         ; 19 ** not used **

 Note that everything from byte 12 (Permitted RAM write start address) on is ignored by 8-bit code: Everything is Read-Write in 8-bit devices.