Rockwell-automation 1771-SPI,D17716.5.122 SPI PROTOCOL INTERFACE Manual de usuario descargar pdf (Pagina 24)

Defining Command and Status Blocks

Chapter 3

3-2

Your ladder logic must send (BTW) a valid MCC to the SPI module after

power-up to prepare it for operation. This can be an MCC header (4 words)

or a complete MCC block (up to 64 words). Only after the SPI module

receives it, can the module operate as follows:

accept any valid command block sent to it by BTW

poll devices on the SPI network

return device-specific status blocks by BTR

return optional system status (SYS) by BTR

Until it receives a valid MCC block, the SPI module can only return the

system status (SYS) block in response to a BTR request.

Important: Your ladder program must always initiate communication with

the SPI module at power-up with the MCC.

Table 3.A

Bit/Word

Map of the Module Configuration Command Block (MCC)

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

1 CNE Baud Select CNS NF DF MCC Block ID

2 0 0 Page Number Total Pages

3 and 4 0 0 0 0

The following word pairs (5&6, 7&8, etc.) define SPI network devices.

Important: List them in the order in which you want them polled (queue order).

DS CS PM Reserved Device ID (for first queued BTR)

Zone Address (for temperature control devices, only)

Device Address

DS CS PM Reserved Device ID (for 2nd queued BTR)

Zone Address (for temperature control devices, only)

Device Address

⇓⇓ ⇓ ⇓

DS CS PM Reserved Device ID (for 30th queued BTR)

Zone Address (for temperature control devices, only)

Device Address

[ 1 ] DS CS PM Reserved SYS Block ID

Reserved SPI Module Address

[ 1 ]:

ou must add the SYS Block ID (1

111111

1) to the list of device IDs if you want the SPI module to return system status.

If so, add it last in the list.

Module Configuration

Command Block (MCC)

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 61 62

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