Rockwell-automation 1771-SPI,D17716.5.122 SPI PROTOCOL INTERFACE Manual de usuario descargar pdf (Pagina 28)

Defining Command and Status Blocks

Chapter 3

3-6

The custom configuration block (CCB) tells the SPI module the required

configuration for a single device, specified by the device ID in its header.

Your program must transfer a CCB to the SPI module for each custom

device on the SPI network. Then, your program must use custom data

blocks (CDBs) to transfer data to the devices.

Transferring custom configuration, data, and status blocks to/from the SPI

module uses fewer words and a simpler format than SPI-specified standard

blocks. However, you must still configure the SPI module with the MCC.

The SPI module stores custom configuration and data in RAM. If the module

loses power this information is lost, requiring replacement downloads.

The SPI module can store:

up to 10 CCBs for that number of devices

up to 60 bit-command words and/or setpoints per device

Table 3.E

Bit/Word

Map of the Custom Configuration Block (CCB)

Word 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

1 0 CA DC SPIspecified Device ID

2 Number of numeric setpoints Number of bitcommand words

3 Number of bitstatus words Number of ASCII strings

4 Number of ASCII status strings Number of numeric status words

starting at

CMD1 Code (such as 20) CMD2 Code (such as 49)

SPI codes CDM1 and CDM2 define the specific bitcommand word that your program will load into word 5 of the CDB.

If you have more codes of this type, load them in the next consecutive words. Leave no blank words.

The number of bitcommand words that you entered in word 2 bits 07 must be identical to the number of:

# code words (such as word 5 of this block)

# bitcommand words that your program will load into the CDB starting with word 5.

⇓⇓⇓⇓⇓⇓⇓

(hih)

CMD1 Code (such as 20) CMD2 Code (such as 31)

(or higher)

SPI codes CDM1 and CDM2 define the specific numeric setpoint that your program will load next into the CDB.

If you have more codes of this type, load them in the next consecutive words. Leave no blank words.

The number of numeric setpoints that you entered in word 2 bits 815 must be identical to the number of:

# code words (such as word 6 of this block)

# numeric setpoints that your program will load into the CDB following the bitcommand words.

⇓⇓⇓⇓⇓⇓⇓

(hih)

CMD1 Code (such as 20) CMD2 Code (such as 22)

(or higher)

SPI codes CDM1 and CDM2 define the specific ASCII string that your program will load next into the CDB.

If you have more codes of this type, load them in the next consecutive words. Leave no blank words.

The number of ASCII strings that you entered in word 3 bits 07 must be identical to the number of:

# code words (such as word 7 of this block)

# ASCII strings that your program will load into the CDB following the numeric setpoints.

⇓ Repeat for bit,numeric,and ASCIIstatus codes that you want returned in the CDS during automatic polling. ⇓

64 CMD1 Code (such as 20) CMD2 Code (such as 3C)

Custom Configuration

Block (CCB)

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 61 62

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