MVI56-DH485R
♦
ControlLogix Platform
Reference
DH485 Interface Module for Remote Chassis
User Manual
Page 62 of 97
ProSoft Technology, Inc.
August 27, 2009
The number of blocks requested by the module from the processor depends on
the number of read registers configured for the module. If the module is
configured for 600 registers, 15 blocks (1000 to 1014) will be requested. This
data will be placed in the module’s internal database starting at the read register
configured for the module.
Use of this feature requires ladder logic to process the blocks requested. The
example ladder logic displays a rung that will handle this optional feature.
Change Command Type Control Block
Blocks 3000, 3001, 3002, 3100, 3101 and 3102 alter the command type for
entries in the user command list. When commands are processed during the
startup of the module, the command type is set to the value specified in the
configuration file. These control blocks alter the configured command type.
Each block contains a command index list. The values entered in this list
correspond to the indices of the commands configured by the user. The first
command in the user command list has an index of 0 and the second has in
index of 1. Therefore, to alter the command type of commands 3 and 5, set the
number of command indexes (word 1) to 2 and enter the values 3 and 5 in words
2 and 3. Each block can handle up to 40 commands in the list.
Block 3000 and 3100 requests change the commands listed in the block to the
disable type (type = 0). Block 3000 is used for Port 0 and 3100 is used for Port 1
commands. The format for the request block from the ladder logic is as follows:
Offset Description
Length
0
3000 or 3100
1
1
Number of command indexes
1
2 to 41
Command index list
40
The response block from the module to the processor has the following format:
Offset Description
Length
0
Write Block ID
1
1
Number of commands processed
1
2 to 40
Spare
39
41
3000 or 3100
1
Block 3001 and 3101 requests change the commands listed in the block to the
enable type (type = 1). Block 3001 is used for Port 0 and 3101 is used for Port 1
commands. The format for the request block from the ladder logic is as follows:
Offset Description
Length
0
3001 or 3101
1
1
Number of command indexes
1
2 to 41
Command index list
40
The response block from the module to the processor has the following format:
Offset Description
Length
0
Write Block ID
1
1
Number of commands processed
1
