
4. FUNCTIONS
MELSEC-A
4-12
(2)
OUTPUT area
Either normal service mode or extended service mode can be selected via the mode switch on
the main unit.
(a)
Normal service mode (MODE Switch : No. 0)
This is the area that stores the output data to the slave station.
This area is fixed to an allocation of 32 bytes (16 words) per station for a total of 60 stations
worth. This output area configuration is as follows.
Example : When the output data length for the first station is set to 1 bytes and that for the
second station to 3 bytes
Address
Address
960/3C0h
975/3CFh
976/3D0h
991/3DFh
1904/770h
1919/77Fh
1st station output data
2nd station output data
n th station output data
60th station output data
1st station 1st byte
b15
b0
960/3C0h
961/3C1h
974/3CEh
975/3CFh
2nd station 2nd byte
2nd station 1st byte
2nd station 3rd byte
976/3D0h
977/3D1h
991/3DFh
b15
b0
(Upper byte)
(Lower byte)
: Free area (00h)
*1: Since the data area is fixed to 32 bytes,
all unused areas will become free.
*1
*1
(b)
Extended service mode (MODE switch : No. E)
This is the area that stores the output data to the slave station.
In this area, the data length (in byte units) for each station is assigned in variable length
according to the parameter file set in the configurator software package.
The data length can be set in the range of 0 to 244 bytes.
Number of stations that can be set will vary in the range of 1 to 60, depending on the
specified data length. For example, seven stations can be set if the data length for each
station is 244 bytes, and 60 stations if the data length is 32 bytes.
Example : When the output data length for the first station is set to 19 bytes and that for the
second station to 5 bytes
Address
Address
1st station output data
2nd station output data
n th station output data
60th station output data
1st station 2nd byte
1st station 4th byte
1st station 1st byte
1st station 3rd byte
1st station 18th byte
1st station 17th byte
1st station 19th byte
2nd station 2nd byte
2nd station 4th byte
2nd station 1st byte
2nd station 3rd byte
2nd station 5th byte
b15
b0
*2
b15
b0
: Free area (00h)
*2: When the data lenghth is set to an odd number
of bytes, the last upper byte becomes a free area
and data for the next station is assugned from
the next address.
(Upper byte)
(Lower byte)
960/3C0h
968/3C8h
969/3C9h
970/3CAh
971/3CBh
972/3CCh
961/3C1h
960/3C0h
969/3C9h
970/3CAh
972/3CCh