Serial Communication Calculator

Serial communication sends data one bit at a time over a wire — and the timing of each bit, character, and message determines how fast a network of devices can exchange data. Enter your baud rate, frame format (data bits, stop bits, parity), message lengths, and network parameters like number of devices, slave response delay, and inter-message overhead into the Serial Communication Calculator to get the Total Cycle Time for a full network poll. Secondary outputs include bit time, character time, request time, response time, and poll time per device.

Communication speed of the serial bus

Number of data bits per character

Number of stop bits per character

Parity setting for error checking

bytes

Total bytes in a typical request message

bytes

Total bytes in a typical response message

slaves

Number of slave devices on the bus

ms

Time slave takes to process request

ms

Signal travel time for full network length

Additional delay between messages

Results

Total Cycle Time

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Bit Time

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Character Time

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Request Time

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Response Time

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Poll Time (per device)

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Frequently Asked Questions

What is baud rate in serial communication?

Baud rate is the number of signal units (symbols) transmitted per second in a serial communication channel. It determines the speed at which data can be transmitted between devices. For example, a baud rate of 9600 means 9600 symbols can be transmitted per second.

How do I calculate character time from baud rate?

Character time is calculated by dividing the total bits per character by the baud rate. Total bits include start bit (1), data bits (7 or 8), parity bit (0 or 1), and stop bits (1 or 2). For example, with 8 data bits, no parity, 1 stop bit at 9600 baud: Character time = 10 bits / 9600 = 1.04 ms.

What affects the total polling cycle time?

Polling cycle time is affected by: request message length, response message length, slave response delay, network propagation delay, inter-message overhead, and the number of devices being polled. Each device adds one complete poll time to the total cycle.

Why is slave response delay important?

Slave response delay is the processing time a slave device needs to interpret a request and prepare its response. This varies by device complexity and can significantly impact overall communication timing, especially in networks with many devices or complex slave operations.

What baud rate should I use for my application?

Common baud rates include 9600, 19200, 38400, 57600, and 115200. Choose based on your distance requirements, noise environment, and timing needs. Higher baud rates allow faster communication but may be less reliable over long distances or in noisy environments.

How does parity affect communication timing?

Adding parity (even or odd) increases each character frame by one bit, which proportionally increases character time and overall message transmission time. While parity provides error detection, it comes at the cost of slightly slower communication.