Emerson FXMP25 User Manual page 26

Suitable USB to EIA485 and EIA232 to EIA485 isolated converters are available from
Control Techniques as follows:
• CT USB Comms cable (CT Part No. 4500-0096)
• CT EIA232 Comms cable (CT Part No. 4500-0087)
When using one of the above converters or any other suitable converter with the
FXMP25, it is recommended that no terminating resistors be connected on the network.
It may be necessary to 'link out' the terminating resistor within the converter depending
on which type is used. The information on how to link out the terminating resistor will
normally be contained in the user information supplied with the converter.
4.8.3 Serial communications set-up parameters
The following parameters need to be set according to the system requirements.
This parameter defines the communications protocol used by the 485 comms port on
the drive. This parameter can be changed via the drive keypad, via a Solutions Module
or via the comms interface itself. If it is changed via the comms interface, the response
to the command uses the original protocol. The master should wait at least 20 ms
before sending a new message using the new protocol. (Note: ANSI uses 7 data bits, 1
stop bit and even parity; Modbus RTU uses 8 data bits, 2 stops bits and no parity).
NOTE
When using the CT EIA232 Comms cable the available baud rate is limited to
19.2 k baud.
Parameters Pr 95 and Pr 96 select the address and baud rate respectively as detailed in
section 6 Parameters on page 30.
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FXMP25 User Guide
Issue Number: 3