20 pad (word 32), 21 hart configuration word (word 33), Reserved for future expansion – Spectrum Controls 1769sc-HART Modules User Manual
Page 62: 16 bit alignment (set to zero)
Compact IO™ Isolated HART Analog Output Module
User’s Manual 0300217-03 Rev. A
6-10
Note: The number of counts entered for a channel’s ramp rate may be equal to 0 only
if ramping is not enabled for the channel.
6.3.19 Spare (Words 7, 15, 23, 31)
Reserved for future expansion
6.3.20 Pad (Word 32)
16 bit alignment (Set to Zero)
6.3.21 HART Configuration Word (Word 33)
Word 33 is used to configure module properties like enabling and disabling HART,
setting a HART handle time for HART messaging, and selecting one of three scanning
schemes for HART pass-through messages. The table below shows the available settings
for word 33.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Dis able
0
En abled
1
Dis able
0
En abled
1
Dis able
0
En abled
1
Dis able
0
En abled
1
Tw o Ch an ne l S c an s
0
0
On c e Pe r Mod ule Sc an
0
1
Ev er y Cha nn el Sc a n
1
0
Re s e r ve d
Se t to Z e r o
0
0
Pas s - T h r o u g h Sch e m e
To S elec t
Han d le T im e o u t
M ak e thes e bit s ettings
H andle Tim eout (1 to 255 s ec )
C H0 HA RT En a b le
C H1 HA RT En a b le
C H2 HA RT En a b le
C H3 HA RT En a b le
Handle Timeout
There is a handle timeout associated with the final reply message. After the module
obtains the requested information from the HART device, it will start the Handle Timeout
timer. The reply message will be kept in memory during the Handle Timeout period.
After the timeout occurs or after the message is retrieved by the pass-through response
query command, the storage buffer will be discarded, and another pass through message
will be serviced without being rejected. Handle Timeout is in the range of 0 to 255
seconds.
Note: A handle timeout of zero is valid. When set to zero, the handle timeout will
default to 10 seconds.
Channel HART Enable (Bits 8, 9, 10, 11)
These bits allow the user to enable HART on channels 0 through 3, respectively.
Pass-Through Scheme
The pass-through scheme determines how often the pass through commands are serviced.
Two Channel Scans: Pass-through serviced once every two channel scans
Once Per Module Scan: Pass-through serviced once per module scan
Every Channel Scan: Pass-through serviced once every channel scan
Note: The pass-through scheme can increase the HART packet update time if pass-
through messages are serviced every channel scan.