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MVI56-MCM
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ControlLogix Platform
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Modbus Communication Module
Page 10 of 159
ProSoft Technology, Inc.
July 24, 2008
Note: You can install the module in a local or remote rack. For remote rack installation, the module
requires EtherNet/IP or ControlNet communication with the processor.
2.2 Deployment
Checklist
Before you begin configuring the module, consider the following questions. Your
answers will help you determine the scope of your project and the configuration
requirements for a successful deployment.
1
____________ Are you creating a new application or integrating the module
into an existing application?
Most applications can use the Sample Ladder Logic without any edits to the
Sample Program.
2
____________ What slot number in the chassis will the MVI56-MCM module
occupy?
For communication to occur you must enter the correct slot number in the
sample program.
3
____________ Are RSLogix 5000 and RSLinx installed?
RSLogix and RSLinx are required to communicate to the CLX processor
(1756-L1, L55, L61 & L63). Sample Ladder programs are provided for many
versions of RSLogix 5000.
4
____________ How many words of data do you need to transfer in your
application (from ControlLogix to Module / to ControlLogix from Module)?
The MVI module can transfer a maximum of 5000 (16-bit) registers to/from
the CLX processor. The Sample Ladder transfers 600 words to the CLX
processor (into the Read Data array) and obtains 600 words from the CLX
processor (from the Write Data array)
5
____________ Will you be using the module as a Modbus Master or Modbus
Slave? Will you be transferring data using Modbus RTU or Modbus ASCII?
Modbus is a master/slave network. Only one master is allowed on the Com
line (max 32 devices/RS485). The Master is responsible for polling data from
the slaves on the network.
6
____________ For a Modbus Master, what devices (node ID) and Modbus
addresses do you need to exchange data with on the Modbus network?
As a Modbus master, you must know the node ID # of the slave devices you
wish to obtain data from, as well as the Modbus address (coil 0001, register
4001 etc) of the data that must be read from or written to that slave device.
7
____________ For a Modbus Slave, how many words or bits of data do you
need to send to the master device?
The MVI module can send data to a Modbus master as 0x coil data, 1x input
coil data, 3x input registers and 4x holding registers. The sample program
transfers 600 (16-bit) words or 9600 bits to the CLX processor, and 600w or
18 bits from the CLX processor.