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Chapter 8 Communication Functions
8-65
3) Example program 2
It’s supposed that MASTER-K120S main unit is the master and it reads Coil Status of the station no. 17, a Modicon product.
The master reads status of the input contact 10197 ~ 10218 of the slave station no. 17.
The input contact of the slave station is supposed to be as follows and the data that are read is saved in M015.
Input
10220 10219 10218 10217 10216 10215 10214 10213 10212 10211 10210 10209
Status X X 1 1 0 1 0 1 1 1 0 1
Hex 3 5 D
Input
10208 10207 10206 10205 10204 10203 10202 10201 10200 10199 10198 10197
Status 1 0 1 1 1 0 1 0 1 1 0 0
Hex B A C
• The status of input contact 10219,10220 are redundancy.
• Data is sent starting from the low bit by byte unit. If the deficient bit of a byte is filled with 0. An example of sending the
above data is as follows.
Example 2) AC DB 35
① : It designates slave station and function code ( No. of station : h11(17) , function code : h02 )
② : Address setting
Address ‘0’ at MODBUS protocol means address ‘1’ actually .So if you want to designate address ‘10197’ ,
write address ‘10196’
③ : Reading number setting ( Reading number is 22 from 10197 to 10220.)
④ : This is MODBUS Communication instruction.
The data transmission starts lower byte. The remnant part of byte is filled with ‘0’
⑤ Stored data at D200,D201 are :
Device Stored data
D200 h AC DB
D201 h 00 35
①
②
③
④