Modbus Remote Io Control Applications (Use Modrw) - Delta C2000 Series User Manual

Chapter 16 PLC Function ApplicationsC2000

16-12 Modbus Remote IO Control Applications (use MODRW)

The C2000's internal PLC supports 485 read/write functions, which can be realized using the
MODRW command. However, the 485 serial port must be defined as available for the PLC's 485 use
before writing a program, and the Pr. 09-31 must be set as -12. After completing settings, the
standard functions defined by 485 can be used to implement read/write commands at other stations.
Communications speed is defined by parameter 09-01, the communications format is defined by Pr.
09-04, and the PLC's current station number is defined by Pr. 09-35. The C2000 currently supports
the functions read coil (0x01), read input (0x02), read register (0x03), write to single register (0x06),
write to several coils (0x0F), and write to several registers (0x10). Explanations and the usage of
these functions are provided as follows:
MODRW command
S1 S2 S3
Node
Address
Command
ID
K3 H01 H500
K3 H02 H400
K3 H03 H600
K3 H06 H610
K3 H0F H509
K3 H10 H602
※ XX indicates doesn't matter
After implementing MODRW, the status will be displayed in M1077 (485 read/write complete), M1078
(485 read/write error), and M1079 (485 read/write time out). M1077 is defined so as to immediately
revert to 0 after the MODRW command has been implemented. However, any of three situations—a
report of no error, a data error report, or time out with no report—will cause the status of M1077 to
change to On.
Example program: Testing of various functions
At the start, will cause the transmitted time sequence to switch to the first data unit.
0 M1002
On only for 1 scan a
S4 S5 General
meaning
Return:
Length
D area
Read coil
D0 K18
(bit)
Read input
D10 K10
(bit)
Read register
D20 K3
(word)
Write to single
D30 XX
register (word)
Write to
D40 K10 multiple coils
(Bit)
Write to
D50 K4 multiple
registers (word)
Slave device is Delta's PLC
meaning
Read 18 bits of data corresponding to
slave station 3 PLC Y0 to Y21. This
data is stored by bit 0 to 15 of the this
station's D0 and bit 0 to bit 3 of D1.
Read 10 bits of data corresponding to
slave station 3 PLC X0 to X11. This
data is stored by bit 0 to 9 of this
station's D10.
Read 3 words of data corresponding
to slave station 3 PLC T0 to T2. This
data is stored by D20 to D22.
Write slave station 3 PLC's T16 to this
station's D30 value
Write slave station 3 PLC's Y11 to
Y22 to bit 0 to 9 of D40.
Write slave station 3 PLC's T2 to T5 to
D50 to D53
K1
MOV
16-156
Slave device is Delta's
converter meaning
Does not support this function
Does not support this function
Read 3 words of data
corresponding to slave station
3 converter parameters 06-00
to 06-02. This data is stored by
D20 to D22
Write slave station 3 converter
06 to 16 parameter to this
station's D30 value
Does not support this function
Write slave station 3 converter
06-02 to 06-05 parameters to
this station's D50 to D53
K4M0