Cameron NUFLO MC-III, User Manual

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A-4
Appendix A MC-III™ Panel Mount Flow Analyzer
Auto-Negotiate Option
When connected devices are capable of switching baud rates automatically or when devices are directly
connected to an MC-III Panel Mount, a user may configure the MC-III interface to automatically negotiate the
fastest baud rate during device connection. This “negotiated” baud rate does not replace the configured baud
rate, but rather provides a temporary boost of baud rate while the computer is connected to the device for
faster downloads. After the software disconnects, the device reverts to the configured baud rate.
By default, this function is disabled. To enable automatic baud rate negotiation on device connect, check the
“Attempt auto-negotiation….” check box in the Communications Option screen ( Figure A.4, page A-3 )
and click “OK”. To initiate an immediate search for the fastest baud rate without exiting to the Welcome
screen, check the “Enable auto-negotiated baud rate” checkbox, click the “Test Now” button to the right of the
checkbox, and click “Yes” at the prompt in the Confirm dialog box.
Enable Auto-Negotiated Baud Rate Option
The “Enable auto-negotiated…” checkbox enables usage of the baud rate that has been automatically selected
or “negotiated” by the software, either upon connection with the instrument or when the “Test Now” button
was last clicked. See also Auto-Negotiate Option above.
Request-to-Send (RTS) Line Option
Some RS-485 to RS-232 converter modules require a request-to-send (RTS) line for switching between a
“receive” and “transmit” state. This checkbox allows the software to toggle this line, ensuring that incoming
data will be readily transmitted and that the converter will not stall in a “receive” mode after a period of
inactivity. By default, this option is enabled. To disable the option, deselect the checkbox and click “OK.”
Enable Modbus Address Support for Firmware Versions 1.06 through 1.08
Operators with MC-III units programmed with firmware versions 1.06 through 1.08 must check the checkbox
labeled “Enable Modbus Address Support for Firmware Versions 1.06 through 1.08” to ensure seamless
Modbus communication with their units. Operators using any other firmware version with the MC-III should
leave the checkbox unchecked.
Timing Parameters
Presend Delay
On the Communications Options screen, a user can enter a presend delay (milliseconds) to help ensure a
successful connection between the computer and the MC-III when the instrument is networked with a radio
or other low-speed device. The computer transmits a request to send, which turns the device on, and then waits
the specified length of time before attempting to transmit data. By default, this parameter is set to zero.
Number of Retries
By default, the computer will make two attempts to connect to the MC-III Panel Mount before providing an
error message. In situations where timeouts are anticipated—for example, due to a slow-speed computer—the
user can increase the length of time allowed for a connection by inputting a larger number in the Number of
Retries field.
Timeout Period Type
A user can select an “optimal” timeout, which is based on the response time of the MC-III Panel Mount
to various requests for data at all baud rates during extensive testing, or a fixed timeout determined by the
user. By default, the “optimal” period type is enabled. When a communication error occurs, the “optimal”
timeout allows the software to respond much faster than the more conservative fixed timeout. The optimal