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Overview
:
This MxM allows Manager to interface with a Rockwell Automation Control Logix family PLC using the CIP Ethernet/IP protocol to read and write symbolic references created in the PLC.
This release of the MxM supports the basic PLC integer types with size 8,16 or 32 bits.
CIP uses a request/response protocol. Each variable configured in the device is polled in order until all variables have been polled and updated, then the list starts again. When polling a long list of variables, this request/response mechanism can cause the variables to update slower than expected. To prevent this delay for timing-critical variables, use separate Devices all pointed to the same PLC, each polling for one or two variables. This breaks up the TCP communication into multiple connections, each with its own list of variables to poll.
The Write Variable command takes priority over polling requests, so variable updates can be temporarily suspended when sending lots of Write Variable commands at the same time.
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Installation
(MXM) :
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Creation
(Device) :
Device creation window :
The setup window allows the user to enter the IP address for the PLC, and provides a mechanism to enter a list of Variables that the user wishes to read from and write to in the PLC. Each PLC variable entered will be given a Medialon variable that can be used to test the current value. Note that the PLC variables can only be changed using the Write Variable command. Setting the value of the Medialon Manager variables using Expressions or other mechanisms will not cause the variable in the PLC to be changed.
Note: When defining symbolic links on the PLC for use with Medialon Manager, it is important to follow the Manager naming conventions to ensure compatibility.
Variable Access Type:
An access type can be specified for each of the variables.
- Read/Write: The "Write Variable" command is allowed and the variable value is updated when its value is received from PLC after a subsequent poll (except for aliases as explained in the NOTE below).
- Write Only: The "Write Variable" command is allowed and the device variable value is set immediately. The device variable value is never polled or updated from the PLC.
- Read Only: The "Write Variable" command has no effect. The variable value is only updated when its value is received from the PLC after a poll from the MxM.
Alias Variables :
Alias variables provide a simple way to handle bit sized flags in integer PLC variables. An alias consists of a name, the name of a PLC variable and the bit position within the PLC variable. Alias variables are mapped to integer variables in Manager, and can take the values 0 or 1. Alias variables can be changed using the Write Variable command.
NOTE: For an alias defined as a bit of a "Read/Write" PLC Variable: The bit value written to the alias is incorporated into the last value of the PLC variable. The resulting value is used to set the PLC Variable value and then is sent to the PLC. This can introduce problems if the PLC modifies the variable between the last polled update and the execution of the Write Variable command (if using Read/Write access, which is not a recommended practice).
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Commands
(List Of) :
Write Variable :
Description
: Sets the value of a Variable in the PLC.
Parameters :
Name: [Type : String] : The name of the symbol (or associated bit Alias) in the PLC. This can only be a Variable or Alias that is configured for Read/Write or Write Only access.
Value : [Type : Integer] : Value to set (for Aliases, the value is limited to 0 or 1).
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Variables
(List Of) :
Status :
Type
: Enum.
Description : Current status of the device connection.
Available Values :
| "Unconnected" | : | Not connected |
| "Connecting" | : | Connection in progress |
| "Ready" | : | Device is connected
and ready to work |
| "Busy" | : |
Device working |
Error :
Type
: Enum.
Description : Current error status of the device.
Available Values :
| "No Error" | : | Device is Ok |
| "Network Error" | : | A network or transmission error occurred |
Additional variables can be created in the setup screen, which mimic variables in the PLC.
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Support
(Difference with previous versions) :
V 1.0.1:
- Added: PLC ENet Slot number can now be specified in the Setup Dialog.
- Added: Alias variables for bit manipulation.
V 1.0.2:
- Fixed: Alias write commands are sometimes not correctly executed if they are fired quickly.
V 1.0.3:
- Added: Now the user can specify the access type for each variable (Read/Write, Write Only, Read Only).
V 6.0.0: - Modified: Support of Manager V6/Showmaster V2.
V 6.0.1:
- Fixed: TCP connection causes a crash.
- Fixed: Setup dialog doesn't open on the correct screen on a multi-screens configuration.
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