Rockwell Automation 1770-HT8 SMART TRANSMITTER - Manual (Page 73)

Communicating with the Smart
Transmitter Interface
Chapter 4
Communicating with the Smart Transmitter
Interface
4-8
Figure 4.5
Unique 38 Bit Device Identifier
90073
Bit
37 31 23 15 7 0
Manufacturer
ID
Manufacturer's
Device Type
Device ID
HART Command
This one-byte field specifies the HART command that is to be sent by the
Smart Transmitter Interface to the field device. Many commands are
device dependent. Table 4.B lists some universal commands supported by
all field devices. Consult the documentation provided with the device for
details. Set this field to a device recognizable command before sending the
packet to the Smart Transmitter Interface.
Table 4.B
Representative HART Universal Commands
Universal
Command
(Decimal)
Description Expected Response
#0 Read Unique Identifier Unique 38 bit device identifier, revision
levels, number of preambles required
#1 Read Primary Variable Primary variable in floating point (IEEE
754 format)
#2 Read Primary Variable Current and
Percent of Range
Primary variable in milliamperes and %
#3 Read Dynamic Variables and Primary
Variable Current
Primary variable and up to 4 predefined
dynamic variables
#6 Write Polling Address Assigned polling address Ć short form
#11 Read Unique Identifier Associated with
Tag
Unique 38 bit device identifier, revision
levels, number of preambles required
Byte Count
This one-byte field indicates the number of bytes to follow this field
excluding the check byte. Valid values are 0 to 113. Insert the number of
bytes required for this packet before transmitting it.