LG Electronics 120S user manual Communication Functions Instruction and example, Modcom

Chapter 8 Communication Functions

8.3.4Instruction and example

1)MODBUS communication instruction(MODCOM)

MODCOM

MODBUS communication

Instruction

Available device

No. of

Flag

M

P

K

L

F

T

C

S

D

#D integer

steps

Error

Zero

Carry

(F110)

(F111)

(F112)

Ch

○

S1	○	○	○	○	○ ○	○	○	○
									7	○
S2
	○	○	○	○	○	○	○	○
S3	○	○	○	○	○	○	○	○

Flag		Designation
			Ch	Designated communication channel
Error	Error flag turns on when designating area is over		S1	Device which is registered communication parameter
(F110)	and the instruction isn’t executed
			S2	Device which stored communication data
			S3	Device which stored communication status

■ MODCOM Ch S1 S2 S3

(1)Example program

•Designate slave station No. , function code,.address, No. of reading

•When input condition(M0020) turns on, MODBUS communication starts.

•Receiving data are stored D1000, and communication status is stored to M100

•When operates as slave, MASTER-K120S responses to master station without commands. And When operates as master, MASTER-K120S sends data in S1 with MODBUS protocol at rising edges of execution condition.

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