Omron C200H-ASC11 Manual page 270

Operating Precautions
Baud Rate for PC Data Transfer
A maximum of 127 words of data can be transmitted in one cycle. If executing PC READ/PC WRITE with data
of a comparatively large size (such as 127 words) and the data is being received using a high baud rate (19.2
kbps or higher), the overlap of data being received and sent will extend the time required to complete the trans-
mission and the cycle time at the PC will also be extended. The effect on the PC cycle time can be minimized
by transmitting a maximum of 20 words per cycle.
Operations after Aborting Program Execution
If a BASIC program that is being executed with an open communications port is aborted by pressing the
Ctrl + X Keys, and data has already been received at the communications port, the return of the prompt after
the LIST display command is executed may be delayed. To stop the delay, after the program execution has
been aborted input the CLOSE command, and then execute the LIST display command.
Executing BASIC Interrupts during Command Execution
When a BASIC program is stopped due to the wait status of a command such as WAIT, a BASIC interrupt will
occur (ON COM, ON PC, etc.) but only one interrupt subroutine will be executed for all BASIC interrupts. All
other interrupts will held and a record made of each.
Program Startup Time
If a program is saved to ROM using ROMSAVE immediately after being debugged, the program memory may
contain garbage. This may cause delays in starting program execution after turn ON the power supply. If this
occurs, save the program at a terminal, load the program from the terminal, and then use ROMSAVE.
Power Interruptions or Restarts during Program Memory Operations
Do not allow PC power to be interrupted or restart the CPU Unit while program memory operations are being
performed, including those for LOAD, SAVE, ROMLOAD, ROMSAVE, autoboot, and compiling for RUN. Pro-
gram memory may be destroyed, preventing further operation.
Consumption of User Memory through Repetition of Subroutine
Branching
Observe the following precautions when using the following two items in combination.
• 1: Subroutine using the GOSUB or interrupt command (ON COM, ON KEY, ON PC, ON TIMER, ON
ALARM, ON TIME$, or ON ERROR)
• 2: GOTO, ON ERROR GOTO/RESUME, ON KEY GOTO, or WAIT command
When the subroutine using the GOSUB or interrupt command (1 above) is forced to branch using the GOTO
command (2 above), data will remain in the stack area, consuming the user memory area inside the ASCII
Unit. When this branching is repeated, an OUT OF MEMORY error (B007), one of the BASIC errors, will occur
or the stack area will overflow, which may result in a malfunction of the system operation.
Be sure to design the program so that it always returns to the subroutine after branching using the GOTO com-
mand and exits from the subroutine using the RETURN command. Refer to the following example.
Example:
10 ON ERROR GOTO 100
20 PRINT FRE
30 GOSUB 1000
90 END
100 PRINT ERR,ERL;
110 RESUME 20
1000 A=1/0 'Divide by zero
1010 RETURN
Appendix A
261