The signal and physical line parameters are accessible via three zones:
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The Physical line zone,
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The Signals zone,
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The RTS/CTS delay zone.
This configuration zone appears on the screen as shown below:
In this zone, you can choose between two types of physical line for the serial port on the BMX P34 1000/2000/2010/20102/2020 processors:
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The RS232 line,
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The RS485 line.
This configuration zone appears on the screen as shown below:
In this zone, you can select the signals supported by the RS232 physical line:
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RX/TX
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RX/TX + RTS/CTS DTE mode
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RX/TX + RTS/CTS DCE mode
If the RS485 is configured, the entire zone will be grayed out and the default value is RX/TX.
This configuration zone appears on the screen as shown below:
RTS/CTS delay zone is available only when both RS232 and RX/TX+RTS/CTS check boxes are selected. An RTS/CTS flow control algorithm is selected if the default value is 0 ms. A value different from 0 enables an RTS/CTS modem control algorithm.
The RTS/CTS flow control algorithm (DTE <-> DTE) is different from the RTS/CTS modem control algorithm (DTE <-> DCE) as follows:
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The RTS/CTS flow control algorithm is related to the overflow reception buffer (full duplex).
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The RTS/CTS modem control algorithm deals with the shared transmission process, e.g. a radio modem.
RTS/CTS Flow Control Algorithm
The aim is to prevent a reception buffer overflow.
The RTS output signal of each device is connected to CTS input signal of other device. The transmitter (M340) is authorized to transmit data when receiving the RTS input signal (e.g. another M340) on its CTS input. This algorithm is symmetric and allows full duplex asynchronous communication.
RTS/CTS Modem Control Algorithm
Before a request is transmitted, the sender (M340) activates the RTS signal and waits for the CTS signal to be triggered by the modem. If the CTS is not activated after the RTS/CTS delay, the request is discarded.
