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What causes a conditional command to be issued?

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 difference is that it will not be execut...

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How to configure more than 100 commands per port when using an MVI46-MCM, MVI69-MCM, or the MVI56-MCM as a Modbus master?

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

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What is the purpose of the UseGuardBand/GuardBandTime or InterCharacterDelay parameters in an MCM module?

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 Time" parameters ...

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What are the power requirements for the MVI69 CompactLogix modules?

MVI69 modules require 800ma @ 5 volts and have a Distance Rating of 2 (slots from a power supply) MVI69E modules require 500ma @5 volts and have a Distance Rating of 4MVI69L modules require 450ma @ 5 volts and have a Distance Rating of 4The 24v requirements for all of these MVI ...

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Where are the on-board jumper positions defined for my MVI module?

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....

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How can I configure the module to store and initialize input values on reset or powerup?

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 "Initialize Ou...

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How to avoid slow data updates on a Modbus network with an MVI56(E)-MCM or MVI69-MCM when some Slaves are either not on-line or not functioning correctly?

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 have 10 slaves communicating on the...

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