Spectrum Controls 1734sc-IE2CH - Manual (Page 52)

4-12 Point IO™ 2/4 Channel Analog HART Module
User’s Manual Pub. 0300257-01 Rev. A
Table 4-16 (Reply Data)
HART Ladder Passthrough Query - Reply packet structure
Offset Field Value Definition
0 Status 00 = Success
34 = DR_RUNNING
35 = DR_DEAD Query Status
1 HART Command 0-255 (1 byte) Echo of HART command
2 HART CommStatus (1 byte) HART Reply Status Byte #1
3 HART FieldDeviceStatus
OR
Reason Code if status = 35
(1 byte) HART Reply Status Byte #2
Reason Code is a diagnostic
value returned when message
fails(Status = 35)
4 Data Size 0-255 (1 byte) Number of Data bytes in
reply for HART command
5-257 HART Reply Data … Data bytes returned in data
field of HART reply to
requested command
HART Pass-through “Reason Code” definitions
The HART Pass-through “Reason Code” is a value that is reported when a Pass-through
reply message returns the general “Status” value as 35 (DR_DEAD). It provides the user
a diagnostic code, which is referenced in the table below, describing the possible cause of
the failure. This code will be returned in offset 3 of the reply message for Pass-through
Init or Query messages whenever the “Status” value at offset 0 is equal to 35
(DR_DEAD).
Table 4-17 (Reason Codes)
HART Pass-through Reason Code
Value Definition Notes:
0x81 No response from HART device
0x82 Invalid long frame address
0x83 Invalid HART message checksum
0x84 HART Command not allowed
(blocked by module)
0x85 Invalid Channel selected
0x86 Channel is not HART Enabled
0x87 Channel does not have a device
connected Module has not established HART
communications on this channel
0x89 Size of CIP message too small to
hold size of HART message Module looks at HART Data size field in
request and validates that the incoming CIP
message size is large enough to send all the
data
0x8A Invalid Handle Only applies to a Query message
0x8B Invalid Start Delimiter
Sending a Pass-through Message
The ladder on the following page demonstrates how to send a complete Pass-through
message using ladder. This example sends universal HART command 1 (Read Primary
Variable). For a listing of HART Universal and Common practice commands, see
Appendix B.