ProSoft Technology MVI56E-MCMR - Manual (Page 163)

MVI56E-MCMR ♦ ControlLogix Platform Reference
Modbus Communication Module with Reduced Data Block User Manual
ProSoft Technology, Inc. Page 163 of 225
May 13, 2014
Command Error List Blocks (9950, 9951)
The Get Command Error List special function is applicable only when the
module's port is configured as a Modbus Master. Use block identification codes
9950 for Port 1 or 9951for Port 2 anytime you want to request the Command
Error List for the 100 user-configurable commands that may be sent by that port.
There is a one-to-one correspondence between the position of a command in the
Command List and its corresponding execution status in the Command Error
List. Each word in the Command Error List holds the most recent execution
status of each corresponding command in the M
ODBUS P ORT 1 C OMMANDS or
M ODBUS P ORT 2 C OMMANDS lists, which were configured in the PCB module
configuration file and downloaded to the module. As each command is executed,
whether as part of normal, repetitive polling or if triggered by Command Control,
the status of the most recent execution will be placed in the appropriate word of
the 100-word Command Error List.
The Command Error List is requested using a "Get Attribute Single" service type
MSG instruction. The following illustration shows the MSG instruction
configuration for a Get Command Error List MSG.
The format of the data returned by the Get Command Error List MSG is shown in
the following table.