3. Instruction Set
API
Mnemonic Operands Function
101 MODWR
Write Modbus Data
Type
OP
Bit Devices Word devices Program Steps
X Y M S K H KnX
KnY
KnM
KnS
T C D E F
MODWR: 7 steps
SS2
SX2
SS2
SX2
SS2
SX2
Operands:
S
1
: Device address (K0~K254) S
2
: Data address n: Data to be written
Explanations:
1. MODWR instruction supports COM2 (RS-485).
2. MODWR is an instruction exclusively for peripheral communication equipment in MODBUS
ASCII/RTU mode. The built-in RS-485 communication ports in Delta VFD drives (except for
VFD-A series) are all compatible with MODBUS communication format. MODRD can be used
for communication (write data) of Delta drives.
3. If the address of S
2
is illegal for the designed communication device, the device will respond
with an error, PLC will record the error code in D1130 and M1141 will be ON. For example, if
8000H is invalid to VFD-B, M1141 will be ON and D1130 = 2. For error code explanations,
please see the user manual of VFD-B.
4. The feedback (returned) data from the peripheral equipment will be stored in D1070 ~ D1085.
After data receiving is completed, PLC will check the validity of the data automatically. If there is
an error, M1140 will be ON
5. If peripheral device receives a correct record (data) from PLC after M1140/M1141 = ON, the
peripheral device will send out feedback data and PLC will reset M1140/M1141 after the validity
of data is confirmed.
6. There is no limitation on the times of using this instruction, but only one instruction can be
executed at a time on the same COM port.
7. If rising-edge contacts (LDP, ANDP, ORP) or falling-edge contacts (LDF, ANDF, ORF) is used
before MODWR instruction, sending request flag M1122 has to be executed as a requirement.
8. For associated flags and special registers, please refer to Points to note of API 80 RS
instruction
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