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Modicon Communication Driver Manual
The following is the format for a register bit reference.
[rr bb]
rr
PLC reference number of the register.
bb
PLC reference number of the bit position. The bit positions are numbered from 1 to 16, least
significant to most significant, respectively. Note that leading 0’s are not required.
Note:
The register number must be followed by a space.
The Operator Station cannot write to inputs or input registers. Therefore, all control button PLC bit
references in the Operator Station editors refer to Modicon coils (or holding/output registers for the
984-785 PLC).
Bit references in expressions refer to Modicon inputs or outputs.
All references to words refer to Modicon registers.
The Modicon PLC models 584, 884 and 984 up to 25 contiguous words per single read. The
maximum number of unused words is 10. The Operator Station generates another read when more
than 10 unused PLC words are encountered.
Examples
The following are examples of valid PLC references which may be assigned in the Operator Station
expression fields.
Word References
Reference Description
[40010] Output register 40010
[30001] Input register 30001
[401000]
Output register 401000
Bit References
Reference Description
[25] Coil
25
[10009] Discrete input 10009
[40098 16] Bit 16 of output register 40098
Note:
Bit writes to 40000 registers cannot be performed.
