| 摘要 |
PURPOSE: An automatic RS232/RS485 communication converter is provided to convert a RS232 signal into a RS485 signal only using transmitting/receiving signals without the necessity of a control signal(/RTS). CONSTITUTION: A RS232 transmitting data input processing unit(10a) converts the transmitting signal of +12 to -12 volts into the electric signal of +5 to 0 volts. A RS232 receiving data output processing unit(20a) converts the receiving signal of 0 to +5 volts into the +12 to -12 volts signals of a RS232 pattern. A clock generation circuit(40) determines communication speed used in the RS232 pattern and a RS485 pattern and generates clocks identical to communication speed determined by a user. A transmitting data shift register(50), synchronized with the clocks generated the clock generation circuit(40), keeps transmitting data, then transmits them in regular sequence after a required time. A transmitting data detection circuit(60) transmits a transmitting/receiving control signal using the clocks generated the clock generation circuit(40) if there is no transmitting data during a required time.
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