2 module input tags used for messaging – Spectrum Controls 1769sc-HART Modules User Manual
Page 80
Compact IO™ Isolated HART Analog Input Module
User's Manual 0300215-03 Rev. A
7-12
Words 4…23 (Message Request Buffer)
The message request buffer contains the data being sent to the module for the current
page (up to 38 bytes).
7.3.2
Module Input Tags Used For Messaging
The module utilizes 22 input words to receive messages and control data flow. The table
below shows the input words used by the module. Refer to Chapter 6 for more
information regarding input words 0 through 27.
Table 7-7 (Module Input Table)
Word/Bit
¹
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
1
2
3
4
5
OS3 OS2 OS1 OS0
S3
S2
S1
S0
6
L3
H3
U3
O3
L2
H2
U2
O2
L1
H1
U1
O1
L0
H0
U0
O0
7
8..27
28
29
30..49
50..71
(1) Changing bit values is not supported by all controllers. Refer to your controller manual for details.
Reserved
Time Stamp Value
Message Response Size
Not Used
Pad (16 bit alignment)
Message Response Buffer
Analog Input Data Channel 0
Analog Input Data Channel 1
Analog Input Data Channel 2
Analog Input Data Channel 3
HART Packet Data
Message Slave Control
Word 28 (Message Slave Control)
Again, the message slave control is used with the message master control to manage
which pages are being sent and what direction the page is going, that is, whether the page
is being sent to the module or read from the module. Refer to Figure 7-5 for the layout.
The message slave control is also used to indicate if a message was rejected by the
module. If a message is rejected, the lower 8 bits will be set (i.e. FF Hex) in the message
slave control. In the event the message is rejected, the message response buffer will
display a fault code in the first byte followed by a checksum in the second. The table
below lists the possible responses:
Table 7-8 (Paging Error Codes)
Error Code
Description
1
A page was sent out of sequence.
2
While processing page 2,3,etc. The message size was different than it
was for page 1.
3
The message size given exceeds the max allowed.
4
The message page data checksum is not correct.
Word 29 (Message Response Size)
The message response size indicates the total number of bytes being returned by the
module.