Spectrum Controls 1734sc-OE2CIH - Manual (Page 40)

4-4 Chapter 4: OE2CIH and HART
User’s Manual Pub. 0300272-01 Rev. A.0
Commands sent at Initial Device Connection
Command: Definition: Comment:
2 Read Loop Current Only sent if Cmd 9 is being used
If any information within a device is changed, the device sets its Configuration Changed
bit (bit 6 of Field Device Status byte), which is detected by the module. The module then
automatically resends the appropriate HART commands to refresh this set of data stored
in the module. The first command sent is Command
38 which will reset the
‘configuration changed’ bit in the device. An Input tag status bit in the module is used to
indicate that the device information has changed. The user may examine this bit and
resend the CIP message to get the latest device information.
Table 4-2 HART Refresh Sequence
Commands sent to refresh Device Information on Configuration Change Detected
Command: Definition: Comment:
38 Reset Configuration Changed Flag
Resets the Configuration Changed
Response Code, Bit 36 of the
Transmitter Status Byte. Secondary
Master devices (address 0) should not
issue this command. Primary Master
devices (address 1) should issue this
command only after the Configuration
Changed Response Code has been
detected and acted upon.
12 Read Message See Table 4-1
13 Read Tag, Descriptor, Date See Table 4-1
15 PV upper and lower range values See Table 4-1
16 Read Final Assembly Number See Table 4-1
48 Read Additional Device Status See Table 4-1
50 Read Dynamic Variable Assignments See Table 4-1
The following table describes the class service code and instances required to send the
Read Additional Device Status message:
The module manages different priority levels of issuing the commands to refresh the
device information data based upon whether pass-throughs are active during this time.
Asset software may be trying to configure the device, or it may be performing a
calibration sequence that needs as much bandwidth as possible
4.2.4 HART Pass-Through Interface
The module will provide a mechanism to send HART messages to a HART device on
any of the channels using the CIP unconnected messaging interface. This is called HART
pass-through because the module is just directly sending the requested HART message to
the HART device and then returning the reply to the requester.
There are three different pass-through interface types made available to support multiple
client requests for pass-through at the same time. The three types are User Ladder,
RSLogix, and Asset SW (Connects or DTM).