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Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

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220 <strong>Practical</strong> Modern <strong>SCADA</strong> Protocols: DNP3, <strong>60870</strong>.5 <strong>and</strong> <strong>Related</strong> <strong>Systems</strong><br />

8.6.1 Process related information elements<br />

The following information elements from Table 8.15 are presented in this sub-section.<br />

Symbol<br />

Description<br />

SIQ<br />

Single-point information with quality descriptor<br />

DIQ<br />

Double-point information with quality descriptor<br />

BSI<br />

Binary state information<br />

SCD<br />

Status <strong>and</strong> change detection<br />

QDS<br />

Quality descriptor<br />

VTI<br />

Value with transient state indication<br />

NVA<br />

Normalized value<br />

SVA<br />

Scaled value<br />

R32-IEEE STD 754 Short floating point number<br />

BCR<br />

Binary counter reading<br />

Table 8.15 Extract A<br />

Process related information elements<br />

SIQ Single point information<br />

SIQ is single point information with quality descriptor. The status bit itself is bit 0. The<br />

4 highest bits provide the quality information per the key below.<br />

7 6 5 4 3 2 1 0<br />

IV NT SB BL SPI<br />

Key<br />

SPI<br />

BL<br />

SB<br />

NT<br />

IV<br />

Status ON<br />

Blocked<br />

Substituted<br />

Not topical<br />

Invalid<br />

DIQ Double-point information<br />

The DIQ is double-point with quality. The quality bits are as previously defined, <strong>and</strong> the<br />

four states of the two status bits are given in the key following.<br />

7 6 5 4 3 2 1 0<br />

IV NT SB BL DPI

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