Publication 1756-UM001A-EN-P - September 2000
13-18
Communicate with Another Controller Over a DH+
™
Network
Step 6: Stagger the
Messages
As you add messages to your project, you may have to coordinate the
execution of the messages. To avoid errors and assure that each
message is processed, follow these rules:
If the number of messages in your application exceeds rules 1 and 2,
then stagger the execution of your messages. Here are some options:
•
Send each message in sequence
•
Send the messages in groups that are within the limits of rules 1
and 2
Step 7: Access
ControlLogix Data
Complete this step for any message that a PLC-5 or SLC 500 controller
sends to a ControlLogix controller over a DH+ network.
Rule 1:
Enable no more than 16 messages at one time (including block transfers).
Rule 2:
Enable no more than 10 of the following types of messages at one time:
•
CIP data table reads or writes that are
not
cached
•
CIP generic
•
PLC2, PLC3, PLC5, or SLC (all types)
•
block transfer reads or writes that are
not
cached
If the controllers are on: And there is:
Then the message is:
same network
only one ControlLogix controller in
the chassis
local
more than one ControlLogix
controller in the chassis
remote
different networks
remote
Summary of Contents for Allen-Bradley ControlLogix 1756-L Series
Page 1: ...ControlLogix System 1756 Lx User Manual ...
Page 10: ...Publication 1756 UM001A EN P September 2000 Table of Contents vi ...
Page 64: ...Publication 1756 UM001A EN P September 2000 4 16 Communicate with 1756 I O Notes ...
Page 152: ...Publication 1756 UM001A EN P September 2000 11 4 Monitor Connections Notes ...
Page 160: ...Publication 1756 UM001A EN P September 2000 12 8 Communicate with a DeviceNet Device Notes ...
Page 204: ...Publication 1756 UM001A EN P September 2000 15 16 Communicate Over a Remote I O Network Notes ...
Page 266: ...Publication 1756 UM001A EN P September 2000 21 10 Maintain the Battery Notes ...
Page 286: ...Publication 1756 UM001A EN P September 2000 B 18 Estimate Execution Time Notes ...
Page 300: ...Publication 1756 UM001A EN P September 2000 C 14 Estimate Memory Use Notes ...
Page 305: ......
Page 307: ...ControlLogix System User Manual ...