Automatic-rs-232-dataselector
This data selector utilizes a single RS-232 port to connect two RS-232 devices (such as printers or plotters) to a mini or microcomputer. The operation is straightforward. When powered on, it resets FFI (QFFT ~ Low), which activates gates N1, N5, and N7, enabling communication between the computer and device B. The detection of the switch command, specifically the Control B character ~ CHR$(2), which can be selected using wire-wrap pins on the parallel outputs of the UART (IM 6402 or equivalent), will set QFFT ~ High. Gates N2, N5, and N7 remain open, allowing device A to stay connected to the computer until the Control B character is detected again. Transistor Q1 converts RS-232 levels to TTL levels, while two LEDs indicate whether device A or B is currently linked. The baud-rate generator provides the required 16x clock for the UART, supporting baud rates from 50 to 19200. Manual control of the selector is facilitated by toggle switch S1.
The data selector circuit is designed to effectively manage communication between a mini or microcomputer and two RS-232 devices, ensuring that only one device is active at any given time. The core functionality relies on the RS-232 protocol, which is standard for serial communication. Upon powering the device, the initial state is established by the FFI reset, which allows for the selection of device B for communication.
The gates N1, N5, and N7 are crucial for directing the data flow, enabling the selection of device B immediately after power-up. Once the Control B character is detected, the state of QFFT changes, allowing for the transition to device A. This switching mechanism is vital for maintaining efficient communication without the need for multiple RS-232 ports.
Transistor Q1 plays an essential role in level shifting, converting the higher voltage levels of RS-232 signals to the lower TTL levels that the microcontroller can process. This ensures compatibility between the devices, allowing for seamless data transfer. The inclusion of two status LEDs provides visual feedback, indicating which device is currently active, thereby enhancing user experience and troubleshooting.
The baud-rate generator is a significant component of this circuit, as it determines the speed of communication between the devices. By offering a range of baud rates from 50 to 19200, the circuit can accommodate various applications and device specifications. The manual control option via toggle switch S1 adds flexibility, allowing users to override automatic switching when necessary.
Overall, this data selector circuit is a practical solution for managing multiple RS-232 devices with a single connection to a computer, optimizing both hardware resources and communication efficiency.With this dataselector, only one RS-232 port is used to connect two RS-232 devices (i.e., printer, plotter, etc.) with a mini-or microcomputer. The operation is very simple. Power on will reset FFI (QFFT ~ Low), which enables gates N1, N5, and N7. Now communication between computer and device B is possible. Detection of the switch command, i.e., Control B character ~ CHR$(2), selectable with wirewrap pins, on the parallel outputs of the UART (IM 6402 or equivalent) will set: QFFT ~ High.
Gates N2, N5, and N7 are open, so device A is connected with the computer until Control B character is detected again. Transistor Q1 converts RS-232 levels to TTL levels while two LEDs indicate whether device A orB is linked.
The baud-rate generator provides the 16 x clock needed for the UART. Any baud rate ranging from 50 to 19200 can be selected. Manual control of the selector is available with toggleswitch Sl.
The data selector circuit is designed to effectively manage communication between a mini or microcomputer and two RS-232 devices, ensuring that only one device is active at any given time. The core functionality relies on the RS-232 protocol, which is standard for serial communication. Upon powering the device, the initial state is established by the FFI reset, which allows for the selection of device B for communication.
The gates N1, N5, and N7 are crucial for directing the data flow, enabling the selection of device B immediately after power-up. Once the Control B character is detected, the state of QFFT changes, allowing for the transition to device A. This switching mechanism is vital for maintaining efficient communication without the need for multiple RS-232 ports.
Transistor Q1 plays an essential role in level shifting, converting the higher voltage levels of RS-232 signals to the lower TTL levels that the microcontroller can process. This ensures compatibility between the devices, allowing for seamless data transfer. The inclusion of two status LEDs provides visual feedback, indicating which device is currently active, thereby enhancing user experience and troubleshooting.
The baud-rate generator is a significant component of this circuit, as it determines the speed of communication between the devices. By offering a range of baud rates from 50 to 19200, the circuit can accommodate various applications and device specifications. The manual control option via toggle switch S1 adds flexibility, allowing users to override automatic switching when necessary.
Overall, this data selector circuit is a practical solution for managing multiple RS-232 devices with a single connection to a computer, optimizing both hardware resources and communication efficiency.With this dataselector, only one RS-232 port is used to connect two RS-232 devices (i.e., printer, plotter, etc.) with a mini-or microcomputer. The operation is very simple. Power on will reset FFI (QFFT ~ Low), which enables gates N1, N5, and N7. Now communication between computer and device B is possible. Detection of the switch command, i.e., Control B character ~ CHR$(2), selectable with wirewrap pins, on the parallel outputs of the UART (IM 6402 or equivalent) will set: QFFT ~ High.
Gates N2, N5, and N7 are open, so device A is connected with the computer until Control B character is detected again. Transistor Q1 converts RS-232 levels to TTL levels while two LEDs indicate whether device A orB is linked.
The baud-rate generator provides the 16 x clock needed for the UART. Any baud rate ranging from 50 to 19200 can be selected. Manual control of the selector is available with toggleswitch Sl.