Cameron NUFLO MC-III - Bus Delay; Bus Timeout; Software Communication Options

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MC-III™ Panel Mount Flow Analyzer Section 4
fastest baud rate during device connection. This “negotiated” baud rate does not replace the congured 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 congured baud rate.
By default, this function is disabled. To enable automatic baud rate negotiation on device connect, choose
Options/Program Options from the menu bar, select Communications from the dropdown options list, check
the “Attempt auto-negotiation...” checkbox, and click “OK” (Figure 4.19). To initiate an immediate search
for the fastest baud rate without exiting tto 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
Conrm dialog box. See also Auto-Negotiate Option, page A-4.
Figure 4.19—Communications Options screen
Bus Delay
Bus delay is the amount of time (in milliseconds) that passes before the MC-III Panel Mount attempts to
take control of the RS-485 bus and transmit a message back to the requesting device. The MC-III Panel
Mount responds very quickly to incoming Modbus
®
requests—in some cases, too quickly. A congurable
delay allows the user to control this response time. A setting of 10 ms is normally sufcient, but may require
adjustment when the device is communicating with a radio or other end device that responds more slowly.
Bus Timeout
Bus timeout is the amount of time (in milliseconds) that must pass to cause the MC-III Panel Mount to reset
its internal Modbus
®
message handler. The default value of 50 ms is normally sufcient.
Software Communication Options
The default timing parameters in the MC-III Panel Mount support communication with most radios and
Modbus
®
devices. However, if the MC-III Panel Mount is used with a device that has a very slow response
time, it may be necessary to adjust the timing parameters to enhance performance. For information about
these parameters, see Appendix A, Software Program Options.