The upper limit of the baud rate depends on the communication specifications
of the connected device, the quality of the cable used, the processing
power (operation speed) of the PC used, and the load (Execute simultaneously
with other programs, etc.).
Also, in the case of RS-422A/485 communication, the cable length can be
extended up to 1200m, but if the communication distance is increased,
the baud rate must be lowered.
Therefore, even if the baud rate is within the baud rate listed in the
device specifications table, communication at a speed exceeding this upper
limit will cause communication errors (overrun, parity, framing).
Confirm the baud rate that can be set by actually communicating with the
diagnostic program.
The baud rate that can be set depends on the specifications of communication
LSI installed on the device.
The overview is shown below, but for details of the baud rate that can
be set, refer to the manual of each device.
The devices in the following table determine the baud rate that can
be set.
Please note that baud rates not listed in the table cannot be set.
Target Device |
Baud Rate |
COM-1(USB)H
|
300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200, 230400, 460800, 921600 |
The devices in the following table can flexibly set the baud rate according
to the reference clock for calculation.
Typical baud rate setting examples are shown in the table, but there are
other baud rates that can be set.
Target Device |
Baud Rate bps (b/s) |
Reference clock for calculation |
||
Minimum Value |
Maximum Value |
Setting Example |
|
|
COM-4CN-USB
|
300 |
921600 |
300, 600, 1200, 2000, 2400, 4800, 9600, 19200, 38400, 76800 Setup error 0.1603% |
48,000,000 |
COM-1C-LPE COM-2PC-PE COM-1(LPCI)H
|
15 |
921600 |
15, 50, 75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, 57600, 76800, 115200, 153600, 230400, 460800, 921600 |
921,600 |
COM-1PDH-LPE
|
30 |
921600 |
30, 50, 75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, 57600, 76800, 115200, 153600, 230400, 460800, 921600 |
921,600 |
COM-2CL-PCI
|
15 |
230400 |
15, 50, 75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, 57600, 76800, 115200, 153600, 230400 |
921,600 |
* Only supported when used in combination with CPS-BXC200 CPS-COM-1PC
|
15 |
921600 |
15, 50, 75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, 57600, 76800, 115200, 153600, 230400, 460800, 921600 |
921,600 |
(BX-M210 GPIO modelEXT-A and EXT-B) COM-1C |
50 |
115200 |
50, 75, 150, 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 14400, 19200, 28800, 38400, 57600, 115200 |
115,200 |
Set the division register of the LSI installed on the device with an integer value.
If the baud rate to be specified is not an
integral multiple of the reference clock for calculation, the decimal
point is rounded off and set to the LSI frequency division register (Clock
Divisor).
Therefore, depending on the specified baud rate, a setup error may occur
when setting the device baud rate.
In general, if the baud rate error is less
than 1%, serial communication can be performed without error.
However, please make sure that the baud rate is configurable by actually
communicating with the device.
Even if the calculation result of the setting value for the frequency division register is an integer, the maximum baud rate of the device used cannot be exceeded.
<Calculation formula for setting value
to frequency division register>
Division register(Clock Divisor) = Reference clock for calculation
/ Specified baud rate
Reference clock for calculation
= 48,000,000Hz(48MHz), Specified baud rate 9,600[bps]
Since the calculation result is 5,000, the setting to the division
register is 5,000, and no setup error occurs.
(Details)
Division register(Clock Divisor) = Reference clock for calculation
/ Specified baud rate
=
48,000,000Hz / 9,600bps
=
5,000
Operation baud rate[bps] = Reference
clock for calculation / Division registe value that you set
=
48,000,000Hz / 5,000
=
9,600bps
Setup error[%] = ((Operation
baud rate - Specified baud rate) / Specified baud rate) *100
=
((9,600bps - 9,600bps) / 9,600bps) * 100
=
0%
Internal clock for calculation
= 48,000,000Hz(48MHz), Specified baud rate 115,200[bps]
Since the calculation result is 416.66666, the setting to the
division register is 416, a setup error of 0.1603% will occur.
(Details)
Division register(Clock Divisor)
= Reference clock for calculation / Specified baud rate
=
48,000,000Hz / 115,200bps
=
416.66666 * 416 is set to the division
register
Operation baud rate[bps] = Reference
clock for calculation / Division registe value that you set
=
48,000,000Hz / 416
=
115,384.6153bps
Setup error[%] = ((Operation
baud rate - Specified baud rate) / Specified baud rate) * 100
=
((115,384.6153bps - 115,200bps) / 115,200bps) * 100
=
0.1603%