Specifications
Response
The normal response is an echo of the query, returned
after the coil state has been forced.
Field Name Example (HEX)
Slave Address 01
Function 05
Force Data HI FF
Force Data LO 00
Quantity of Coils HI 00
Quantity of Coils LO 01
Error Check (CRC) -
7.10.3 Force/Write Multiple Coils (0F HEX)
This function forces each coil in a sequence of coils to
either ON or OFF. When broadcast the function forces the
same coil references in all attached slaves.
The query message specifies the coils 17 to 32 (speed set-
point) to be forced.
NOTE
Coil addresses start at zero, i.e. coil 17 is addressed as 16.
Field Name Example (HEX)
Slave Address 01 (frequency converter address)
Function 0F (write multiple coils)
Coil Address HI 00
Coil Address LO 10 (coil address 17)
Quantity of Coils HI 00
Quantity of Coils LO 10 (16 coils)
Byte Count 02
Force Data HI
(Coils 8-1)
20
Force Data LO
(Coils 10-9)
00 (ref. = 2000hex)
Error Check (CRC) -
Response
The normal response returns the slave address, function
code, starting address, and quantity of coiles forced.
Field Name
Example (HEX)
Slave Address 01 (frequency converter address)
Function 0F (write multiple coils)
Coil Address HI 00
Coil Address LO 10 (coil address 17)
Quantity of Coils HI 00
Quantity of Coils LO 10 (16 coils)
Error Check (CRC) -
7.10.4 Read Holding Registers (03 HEX)
Description
This function reads the contents of holding registers in the
slave.
Query
The query message specifies the starting register and
quantity of registers to be read. Register addresses start at
zero, i.e. registers 1-4 are addressed as 0-3.
Example: Read 3-03 Maximum Reference, register 03030.
Field Name Example (HEX)
Slave Address 01
Function 03 (read holding registers)
Starting Address HI 0B (Register address 3029)
Starting Address LO 05 (Register address 3029)
No. of Points HI 00
No. of Points LO
02 - (3-03 Maximum Reference is 32 bits
long, i.e. 2 registers)
Error Check (CRC) -
Response
The register data in the response message are packed as
two bytes per register, with the binary contents right
justified within each byte. For each register, the first byte
contains the high order bits and the second contains the
low order bits.
Example: Hex 000088B8 = 35.000 = 15Hz.
Field Name
Example (HEX)
Slave Address 01
Function 03
Byte Count 04
Data HI
(Register 3030)
00
Data LO
(Register 3030)
16
Data HI
(Register 3031)
E3
Data LO
(Register 3031)
60
Error Check
(CRC)
-
7.10.5 Preset Single Register (06 HEX)
Description
This function presets a value into a single holding register.
Query
The query message specifies the register reference to be
preset. Register addresses start at zero, i.e. register 1 is
addressed as 0.
Example: Write to 1-00 Configuration Mode, register 1000.
RS-485 Installation and Set... VLT HVAC Basic Drive Design Guide
76 MG.18.C2.02 - VLT
®
is a registered Danfoss trademark
77