86BI/O Poll Messaging 12BAppendix D: Example Messages
118
I/O Poll Messaging
I/O poll messaging connections utilize an assembly format to group and report data from multiple
objects using a single communications commands. These connections typically are used for quick
reporting of information (run-time). Although I/O poll messaging connections typically report data
faster than explicit messaging connections, they limit your access to the set of attributes (the
exception status and the pressure value) listed in Tables 32 and 33, page 64. The data in I/O poll
m
essaging connections is defined by the Predefin
ed Master/Slave Connection Set [1] and cannot
be altered. Refer to I/O Poll Messaging Connections, page 46, for m
ore information.
One example of I/O poll m
essaging is described on pages 118 to 120. This message describes
how to request the poll response for your transducer and interpret the network’
s response. The
following information applies for the example:
• The example depicts I/O poll messaging.
• The example is a nonfragmented message string.
• The node address of the MKS device (the Slave) is 05.
• The node address of the master device is 01.
• Spaces are shown for clarity only. Do not enter spaces in the actual message string.
Example 1: Sending an I/O Poll Request Message
To send a I/O poll request m
essage, enter the comm
and:
42D
where:
CAN Identifier Field
CAN Data Field
42D
GROUP 2 MESSAGE ID
DESTINATION MAC ID
MESSAGE TYPE ID
0 BYTES
(Empty)
Calculated
hex
value:
Figure 16: I/O Poll Request Message
To calculate the request message components shown in Figure 16:
1.
Calculate the hexadecimal value of the CAN Identifier Field.
Refer to Figure 17. This 11-bit field represents the fixed Group 2 Message ID (bits 10 and 9),
the destination node address (the MKS device) as a hexadecimal number (bits 8 to 3), and the
fixed Message Type ID for an I/O request (bits 2 to 0). The hexadecimal value of the CAN
Identifier Field components is 42D
hex
.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
Need help?
General
