4bcd – IDEC WindSRV User Manual

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examined for a value greater than 9 (A-F hex). If a hexadecimal value
between A and F is found, a range alarm is generated, indicating the
value is not within BCD range. Otherwise, the value is scaled with the
following algorithm:

Result=((Raw_value/999) * Span_egu) + Lo_egu.

Read Algorithm Variables

Lo_egu - the database block's low engineering value.
Span_egu - the span of the engineering values.
Raw_value - the value stored in the field device's register.
Result - the scaled value stored in the database block.

Write Algorithm

Writes to a 3-digit BCD register using the following algorithm:

Result=(((InputData - Lo_egu) / Span_egu) * 999 + .5.

Write Algorithm Variables

Lo_egu - the low engineering value.
Span_egu - the span of the engineering values.
InputData - the database block's current value.
Result - the value sent to the process hardware.

4BCD Signal Conditioning

Description

4-digit Binary Coded Decimal (BCD) value.

Input Range

0 - 9999.

Scaling

Scales 4-digit Binary Coded Decimal values to the database block's
EGU range.

Read Algorithm

Reads from a 4-digit BCD register. The Raw_value is then separated
into four nibbles (4 bits) prior to scaling the value. Each nibble is
examined for a value greater than 9 (A-F hex). If a hexadecimal value
between A and F is found, a range alarm is generated, indicating the
value is not within BCD range. Otherwise, the value is scaled with the
following algorithm:

Result=((Raw_value/9999) * Span_egu) + Lo_egu.

Read Algorithm Variables

Lo_egu - the database block's low engineering value.
Span_egu - the span of the engineering values.
Raw_value - the value stored in the field device's register.
Result - the scaled value stored in the database block.

Write Algorithm

Writes to a 4-digit BCD register using the following algorithm:

Result=(((InputData - Lo_egu) / Span_egu) * 9999 + .5.

Write Algorithm Variables

Lo_egu - the low engineering value.
Span_egu - the span of the engineering values.
InputData - the database block's current value.
Result - the value sent to the process hardware.

8AL Signal Conditioning

Description

8-bit binary number.

Input Range

0 - 255.

Scaling

Scales 8-bit binary values to the database block's EGU range.

Read Algorithm

Reads from a 16-bit register using the same algorithm as 8BN, and
returns a status indicating whether the value is out of range and in an
alarm state, or OK.

Result=((Raw_value/255) * Span_egu) + Lo_egu.

Read Algorithm Variables

Lo_egu - the database block's low engineering value.
Span_egu - the span of the engineering values.
Raw_value - the value stored in the field device's register.
Result - the scaled value stored in the database block.

Write Algorithm

Writes to a 16-bit register using the same algorithm as 8BN, and
returns a status indicating whether the value is out of range and in an

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