Schneider Electric INTERBUS Basic Specifikace stáhnout pdf (Strana 66)

Fieldbus Communications Support

31004624 8/2009

Process Data Flow

During data exchange, the master writes the output image, including the control

word. The high byte of the master’s control word specifies the information requested

from slave devices. The slaves respond with a status word in which the high byte

(selector) value corresponds to that of the control word.

The correspondence of high byte values for the control and status words are shown

in the following figure:

1 output image control word (written by the master)

2 input image status word (transmitted by the NIM)

3 control word high byte (selector)

4 control word low byte (inconsequential value)

5 status word high byte (selector)

6 status word low byte (contains the information requested by the master)

The default control word value (0) will return NIM status and diagnostics information

in the low byte of the status word.

1 2 ... 61 62 63 64 65 66 67 68 69 70 71 ... 169 170

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Schneider Electric INTERBUS Basic Specifikace Strana 66