Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 1420

Operation error
Error code Description
(SD0)
2820H When a block No. is specified, the specified block No. is out of the range, 0 to 319.
When a block No. is specified, the specified step No. is out of the range, 0 to 511.
Use a digit specification to specify a step.
• To specify a step in the current block of an SFC program, use K4S.
• To specify a step in another block of an SFC program, use BL\K4S.
• To specify a step of a sequence program, use BL\K4S.
13 SFC PROGRAM INSTRUCTIONS
1418
13.1 SFC Control Instructions