Rockwell Automation 1756-L55M12, Selection Manual, Page: 43 / 88

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1756-SG001G-EN-P — March 2004
Use a 1756-CP3 cable to connect to the serial port.
Over the serial port, the ControlLogix controller supports 12 message buffers. At most,
you can have 4 simultaneous connected messages and 8 simultaneous unconnected
messages. Or if all the messages are unconnected, you can have 12 simultaneous
messages. If a message is greater than 250 bytes, it is divided across enough buffers to
carry the message, which reduces the number of buffers remaining for other
simultaneous messages.
1756-MVI, -MVID multi-vendor interface module
The multi-vendor interface module provides additional access to serial devices. The
module is programmable to accommodate devices with unique serial protocols.
Modbus support
To use Logix5000 controllers on Modbus, you connect through the serial port and
execute a specific ladder logic routine. The ladder logic routine is available on the CD
for RSLogix 5000 Enterprise programming software. For more information, see
Using
Logix5000 Controllers as Masters or Slaves on Modbus Application Solution ,
publication CIG-AP129A-EN-P.
Cat. No.
Communicatio
n Rate
Connections Cable
Power
Dissipation,
Max. Backplane
Current (mA) at
5V Backplane
Current (mA) at
24V
1756-MVI
Configurable,
depending on
serial protocol PRT1: RS-232
PRT2: RS-232, RS-422, RS-485
PRT3: RS-232, RS-422, RS-485
3 serial adapter cables ship with the
module.
At one end of the cables is a locking-
type RJ-45 connector to the module;
at the other end is a DB-9 male
connector.
4 W 800 mA 3 mA
1756-MVID
(1756-MVI module and API software)
Certifications: UL, CSA (Class I, Division 2, Group A, B, C, D), CE, FM, C-Tick