Rockwell Automation Publication 1756-PM020F-EN-P - January 2019 87
Request Format: [PLC-5 system address] [AND mask] [OR mask] + repeats(1)
• [PLC-5 system address] specifies the word to be modified
• [AND mask] 2 bytes (low byte first) specifying which bits in the word to reset (0=reset to 0)
• [OR mask] 2 bytes (low byte first) specifying which bits in the word to set (1=set to 1)
Reply Format:
no data-only status
See also
Read Modify Write N (CMD=0F, 4F; FNC=79) on page 87
Typed Read (CMD=0F, 4F; FNC=68) on page 88
Typed Write (CMD=0F, 4F; FNC=67) on page 88
Word Range Read (CMD=0F, 4F; FNC=01) on page 88
Word Range Write (CMD=0F, 4F; FNC=00) on page 89
For each 4-field sequence, this RMW-N command performs this
procedure:
1. Copy the specified word.
2. Reset the bits specified in the [AND mask].
3. Set the bits specified in the [OR mask].
4. Write the word back.
Request Format: [no of sets][PLC-5 system address] [mask length][AND mask][OR mask] +repeats(1)
• [no of sets] indicates the number of sets of the following four fields.
• [PLC-5 system address] specifies the word to be modified
• [mask length] specifies 2 or 4 byte masks. For this command, most Logix controllers only support 4-byte
mask; use RMW command (FNC=26) for 2-byte mask
• [AND mask] 2 or 4 bytes (low byte first) specifying which bits in the word to reset (0=reset to 0)
• [OR mask] 2 or 4 bytes (low byte first) specifying which bits in the word to set (1= set to 1)
Reply Format: [data]
[data]
• For a successful command ([STS]=0x00), data may be returned, but the Logix data format is not
documented
• For an unsuccessful command ([STS]=0xF0), a byte (error code) occurs; data may be returned, but the
Logix data format is not documented.
See also
PCCC Commands on page 81
PLC-5 Communication Commands on page 85
Read Modify Write N (CMD=0F,
4F; FNC=79)
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