Spectrum Controls 1769sc-HART Modules - Manual (Page 98)

Compact IO™ Isolated HART Analog Output Module
User’s Manual 0300217-03 Rev. A
7-32
Table 7-12 (HART Pass -Through Request Command)
HART pass through command request – command message packet structure
Field Value Definition
HART Channel Number 0x00 – 0x03 (1 byte) Module input
channel number for
HART command
Command Number 0x01 (1 byte)
The command
number to issue a
HART pass-through
command.
HART Command N bytes
N = Length of message – 2
Contents are as follows:
Start or Delimiter (1 byte): 0x82
Long form Address (5 bytes)
HART Command number (1 byte)
Request Data Count (1 byte)
Data (“Request Data Count” bytes)
Checksum (XOR of all bytes from delimiter on.
Delimiter is included ) The actual HART
command PDU
Table 7-13 (HART Pass-Through Request Reply)
HART pass through command request – reply packet structure
Field Value Definition
HART Channel Number 0x00 – 0x03 (1 byte) Module input
channel number for
HART command
Status (1 byte)
32 = Busy (Queue is already full).
33 = DR_INITIATE
35 = DR_DEAD (bad request) Command status
Count (1 byte) Set to 1
Handle (1 byte)
0 (bad when status is DR_DEAD)
1-255 (good)
The handle for
command complete
query
The command status, the second byte in the reply packet for this module specific
command, can return two different responses, INITIATE, and DEAD. These responses
echo the state of the module at the time the command is sent. The conditions for each
response are as follows:
INITIATE will be sent back under the following conditions:
 Command and HART Channel number are both valid.
 HART channel is enabled and communication has been established, meaning at
least the device addressing information is available.
 Handle is available, meaning no pending handle is still active.
 HART channel is doing regular data sampling only. No pending device
information gathering is active.
 No pending pass-through handle is active, meaning handle timeout has not
occurred yet.
 Device address and delimiter are valid.
 Received CIP word count is large enough for the entire command packet.