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67
REFERENCE 6
COMMAND MODE DATA FORMAT
Data Format
An SMD17E2 requires twenty bytes of Output Data as well as twenty bytes of Input Data. In most cases the
data is represented as ten 16-bit (single) integers. Sixteen bit integers support a range of values from -32,768
to 32,767 or 0 to 65,535. When issuing commands to the SMD17E2, there are several parameters that are
larger than sixteen bits. These parameters are:
Target Position
Programmed Speed
Stopping Distance
Minimum Registration Move Distance
Position Preset Value
Encoder Preset Value
Likewise, when reading data back from a unit while it is in Command Mode, there are values that are larger
than sixteen bits. These data values are:
Motor Position
Encoder Position
Captured Encoder Position
By default, these thirty-two bit parameters and data values are written to and read from the SMD17E2 using
the multi-word format described below. When configuring the SMD17E2, it is possible to program it to use a
32-bit double integer format instead of the custom format shown above.
There are three configuration bits that control the data format when the SMD17E2 is in command mode. The
Binary_Output_Format Bit, controls the format of the programmable parameters written to the SMD17E2
when issuing commands. The Binary_Input_Format bit controls the format of the data values written to the
host controller by the SMD17E2. When either of these parameters are set to their 32-bit signed integer format
settings, the Binary_Endian bit determines if the 32-bit values are stored and transmitted least significant bits
first or most significant bits first. Examples of the formats are given below.
Table R6.1 Position Data Format Examples
The range of values when using the multi-word format is -32,768,000 to 32,767,999. When
used in continuous rotation applications, such as control of a conveyor belt, it is possible to
overflow these values. When any of the three position values overflow, the value of the associ
-
ated data words will become indeterminate. AMCI strongly suggests using the signed 32-bit
integer format for continuous rotation applications.
This chapter covers the formats of the Network Output Data used to command the
SMD17E2 and the formats of the Network Input Data that contains the responses
from the device. The SMD17E2 units require twenty bytes of Output Data as well
as twenty bytes for Input Data.
Multi-Word Format
32 bit Signed Integer
Little Endian Format
32 bit Signed Integer
Big Endian Format
Value First Word Second Word First Word Second Word First Word Second Word
12 0 12 16#000C 16#0000 16#0000 16#000C
-12 0 -12 16#FFF4 16#FFFF 16#FFFF 16#FFF4
1,234,567 1,234 567 16#D687 16#0012 16#0012 16#D687
-7,654,321 -7,654 -321 16#344F 16#FF8B 16#FF8B 16#344F
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