Omron C200H-ASC11 Manual page 269

Operating Precautions
Saving Programs
Never turn OFF the power to the PC while writing the program to flash ROM using the ROMSAVE command
(until the command prompt is displayed at the terminal). Doing so will damage the flash ROM and saving data
may be no longer possible. Therefore, be sure not to disconnect power to the PC while the ROMSAVE com-
mand is being executed.
RS-422A/485 Ports
Port 2 (RS-422A/485) of C200H-ASC21 can be used in 1:N communications, however, full-duplex communica-
tions are not possible with this port.
FCS Command Error Check Code Arithmetic Operation
The calculations for CRC-16 and CRC-CCITT used with the FCS command to determine the error check code
of the character expressions is described below. Check that the equations are the same as those for the exter-
nal devices.
CRC-CCITT: Using XMODEM
All 8-bit data is placed in series, it is then divided by a specific 17-bit binary value (1, 0001, 0000, 0010, 0001),
and the remainder (16-bit) is used as the error check code as shown below. The initial value is 0 (16 bits all 0).
CRC-16: Using MODBUS
All 8-bit data is placed in series, it is then divided by a specific 17-bit binary value (1, 0001, 0000, 0010, 0001),
and the remainder (16-bit) is used as the error check code as shown below. The initial value is –1 (16 bits all 1).
Baud Rate for Receive Data Interrupt
When an ON COM interrupt is used, the baud rate of all ports will be as follows:
Port 1 + port 2 ≤ 38.4 Kbps
If the baud rate is set to exceed this condition, a PORT CONFIGURATION ERROR will be generated.
260
8 bits
MSB LSB
First data
Data
Final data
8 bits
MSB LSB
First data
Data
Final data
Appendix A