LG GLOFA-GM Series User Manual page 239

Chapter 7 Communication function
2) Cnet supported MODBUS Command
Cnet's MODBUS communication driver supports reading/writing commands of Bit & Word areas among
commands used in MODBUS Controller. [Table 7.31] describes the commands supported in Cnet MODBUS
communication driver. Other function codes than described in [Table 7.31] are not responded to.
[Table 7.31] MODBUS communication driver supported function code
Function
code
01 Read Coil Status
02 Read Input Status
03 Read Holding Reg.
04 Read Input Reg.
05 Force Single Coil
06 Preset Single Reg
16 Presel Multi Reg.
Remark
[Note 1] Address area of MODICON Controller has the range of 1~9999. Namely, standard of address start is set
to '1, thus, %M area of GLOFA-PLC is mapped in MODBUS memory from %MW1. 1~9999 can be set in
MODBUS, however, 1~4999 is available for %M area memory as of 10 K-bytes open to MODBUS in
Cnet's MODBUS communication driver.
3) GLOFA PLC Address Mapping
Direct variable areas of GLOFA PLC are %M, %Q and %I areas. MODBUS communication driver has access to
10K-bytes(%MW1 ~ %MW4999) of %M area which is an internal memory area, and all areas of MODBUS are
mapped to %M area. As for data type as agreed with function code of MODBUS Protocol, bit command is
mapped to %MX area and word command is to %MW area, however, access to different area is not allowed.
If bit of MODBUS is read, namely, if Read Coil Status & Read Input Status are read, start address shall be started
in a multiple of 8 (Ex. : 00008, 10008, 00016, 10048...). It is because communication module of GLOFA PLC
dose not allow continuous reading of BIT address to direct variable. Continuous reading command of bit in
MODBUS is processed as changed into reading command of byte block.
Name Address
0xxxx(bit-output)
1xxxx(bit-input)
4xxxx(word-output)
3xxxx(word-input)
0xxxx(bit-output)
4xxxx(word-output)
4xxxx(word-output)
7-120
GLOFA-PLC
[Note1]
address mapping
%MX8~%MX9999
%MX8~%MX9999
%MW1~%MW4999
%MW1~%MW4999
%MX1~%MX4999
%MW1~%MW4999
%MW1~%MW4999
Remark
Bit Read
Bit Read
Word Read
Word Read
Bit Write
Word Write
Word Write