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Modicon Communication Driver Manual
Modicon Word and Bit References
The following section describes the use of Modicon word and bit references in your configuration.
The general word referencing method is:
[plcname,word#format]
The “plcname” is the name of the designated PLC as listed in the PLC Name and Port Table. The
“word” is the reference number (address) of the word or register to be read or written. The “#format”
is a code which specifies the format of the data being read or written. The “plcname” and “#format”
are optional.
The general bit referencing method is:
[plcname,bit]
The “plcname” is the designated PLC as listed in the PLC Name and Port Table. The “bit” is the
reference number (address) of the bit, coil, or input to be written or read.
See the “Word and Bit References” topic in the Configuration Software Online Help for a more
detailed explanation of word and bit references, including format descriptions.
Modicon Micro 84, 184, 384, and 484
The Modicon PLCs listed above use decimal addresses. The Operator Station format default is BIN3.
The following list contains the supported memory types.
0XXX
Coils/discrete
outputs
1XXX Discrete inputs (read only)
3XXX Input registers (read only)
4XXX
Holding/output registers
The following is the format for a register reference.
[rr]
rr
PLC reference number of the register.
The following is the format for an input reference.
[ii]
ii
PLC reference number for an input.
The following is the format for a coil reference.
[cc]
cc
PLC reference number for a coil.
The Operator Station cannot write to inputs or input registers. Therefore, all control button PLC bit
references in the Operator Station’s editors refer to Modicon coils.
Bit references in expressions refer to Modicon inputs or outputs.
All references to words refer to Modicon registers.
Modicon PLC model Micro84 can read up to 16 words per read cycle. Models 184 and 484 will allow
a maximum of 25 contiguous words per read. The maximum number of unused words for the three
above mentioned PLCs is 10. The Operator Station generates another read when more than 10 unused
PLC words are encountered.
