Spectrum Controls 1769sc-HART Modules - Manual (Page 102)

Compact IO™ Isolated HART Analog Input Module
User's Manual 0300215-03 Rev. A
7-34
Table 7-13 (HART Suspend/Resume Reply)
HART Channel Suspend/Resume command request – reply packet structure
Field Value Definition
HART Channel
Number 0x00 – 0x03 (1 byte)
0xFF (-1) Apply to all 8 channels Echo of the HART
channel number
received
Status (1 byte)
00 = SUCCESS
35 = DR_DEAD
Command status
Count (1 byte) Set to 1
Handle 0 Fill byte of zero to
keep command
response common
among all replies.
The command status, the second byte in the reply packet for the module specific
command, can return two different responses, SUCCESS, 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:
SUCCESS will be sent back under the following conditions:
•
Command and HART Channel number are both valid.
•
HART channel number is an enabled channel.
•
The identified HART channel finished all of the start-up connection process.
•
The I/O module will not be checking for matching set of suspend/resume
commands. This means, if already suspended, and receives another suspend,
SUCCESS will be returned still. Similarly if the system is operating as normal,
and receives a resume command, it will ignore the command and continue
operation. This state of operation will not be maintained after power-up or when
configuration changes.
DEAD will be sent back if any of the following conditions is true:
•
Command and HART Channel number are both valid.
•
HART channel is not enabled.
•
HART communication has not been established, meaning that the 5-byte unique
address has not been determined yet, or the module is still obtaining device
information.
•
All other conditioned not generating SUCCESS.
7.4.3 HART Pass-Through Command
The HART Pass-Through Command can be used to send any HART command including
universal, common practice or device specific, directly to a field device. The module in
this case could be considered a HART bridge. There can be two (2) instances of a HART
pass-through message being serviced, meaning the pass-through message queue is 2
deep. The HART pass-through response will be queued the moment the command is
received, if the queue spaces are not already in use, and be dispatched after at least a full
scan is done. In other words, after servicing a pass-through, the HART module will make
sure all enabled HART channels have updated variable values before another pass-
through is placed into service.
All HART pass-through commands require a series of messages to be exchanged. First, a
pass-through command request must be sent to the HART module to initiate the pass-
through command. The HART module will respond to the command request with a
command request reply that includes a handle that can be used to obtain the pass-through