The MVI56-MCM is our general purpose Modbus serial (RTU and ASCII are supported) master/slave solution for ControlLogix, and is the preferred choice when used in the local chassis with the controller, or in a remote chassis via Ethernet. The MVI56... Read More

A conditional command is useful when the same value does not need to be written to the end device continuously, but rather on change.  A conditional write command is scanned based upon its poll rate (like all other commands).  The... Read More

Master command list contains up to 100 individual entries. Event command control blocks may be used to send additional Modbus commands directly from the ladder logic to one of the master ports. Read More

When controller tag array sizes are changed in the ControlLogix platform, RSLogix5000 re-initializes all of the tags within that data type. This sets all values to 0 in all tags within that group. Before changing any controller tag array sizes, the... Read More

A customer wrote: "Prosoft Modbus communication modules for Allen Bradley, like MVI56-MCM, experience timeout problems and polling delays on RS-485 multipdrop networks if slaves are powered off or faulty.  For example, if we... Read More

You can initialize the input data (ReadData) with cached values from the processor on these In-Chassis modules so that these values do not get reset to 0 during a module reset or powerloss. To do this the parameter labeled "Initialize Input Image" or... Read More

Due to timing variations in various Modbus devices, it is possible for a Modbus master to have problems sending write commands to the MCM slave port while having no issues with read commands. In such cases, the "Use Guard Band" and "Guard Band... Read More

On bottom of the circuit board for any MVI products, you' ll find three jumper banks: COM1, COM2, and Setup. Each jumper position is labeled 232, 422 and 485. Read More

Version 1.26 of the MVI56-MCM module firmware has been created to address this issue. This new version of code uses interrupt timing, to drop the RTS line as quick as possible, and enable the module to be ready to receive messages as fast as it can.... Read More

In your controller tags, if MCM.Config.ModDef.ErrStatPtr is 0, then status data is likely overwriting the first 33 words of the MCM's ReadData or WriteData arrays which would typically be used for Modbus data. Enter a value of -1 for this... Read More

On some older modules, setting the baud rate to zero for either Modbus port will cause the entire module to fault. Modbus ports on the MVI56 can be individually enabled or disabled using the controller tag mcm.portx.enabled, where x=the port number... Read More

The two application serial ports provide 1000 volts of electrical isolation between the port and the ControlLogix backplane. The debug/configuration port provides no electrical isolation. Note: None of the ports provide any electrical isolation... Read More

Almost all ProSoft solutions for serial based protocols support RS-232C, RS-485 and RS-422 electrical interface types, but equally important is the 'language' or application layer protocol needed for your application. ProSoft... Read More

The MVI56(E)-MCM is configured via controller scoped tags that are automatically generated when the rung of ladder is imported into RSLogix 5000.  This rung of ladder also contains the AOI that is used to transport data back and forth to the... Read More