Danfoss VLT HVAC Basic Drive FC 101 Design Guide

Example of a request to read coils 33–48 (Status Word)
from follower device 01.
Field Name Example (HEX)
Follower Address 01 (adjustable frequency drive
address)
Function 01 (read coils)
Starting Address HI 00
Starting Address LO 20 (32 decimals) Coil 33
No. of Points HI 00
No. of Points LO 10 (16 decimals)
Error Check (CRC) -
Table 7.21 Query
Response
The coil status in the response message is packed as one
coil per bit of the data field. Status is indicated as: 1=ON;
0=OFF. The LSB of the first data byte contains the coil
addressed in the query. The other coils follow toward the
high order end of this byte and from ‘low-order to high-
order’ in subsequent bytes.
If the returned coil quantity is not a multiple of 8, the
remaining bits in the final data byte is padded with zeros
(toward the high order end of the byte). The Byte Count
field specifies the number of complete bytes of data.
Field Name Example (HEX)
Follower Address 01 (adjustable frequency drive
address)
Function 01 (read coils)
Byte Count 02 (2 bytes of data)
Data (Coils 40-33) 07
Data (Coils 48-41) 06 (STW=0607hex)
Error Check (CRC) -
Table 7.22 Response
NOTICE!
Coils and registers are addressed explicit with an off-set
of -1 in Modbus.
For example, Coil 33 is addressed as Coil 32.
7.10.2 Force/Write Single Coil (05 HEX)
Description
This function forces the coil to either ON or OFF. When
broadcast the function forces the same coil references in
all attached followers.
Query
The query message specifies the coil 65 (parameter write
control) to be forced. Coil addresses start at zero, that is,
coil 65 is addressed as 64. Force Data=00 00HEX (OFF) or
FF 00HEX (ON).
Field Name Example (HEX)
Follower Address 01 (adjustable frequency drive
address)
Function 05 (write single coil)
Coil Address HI 00
Coil Address LO 40 (64 decimal) Coil 65
Force Data HI FF
Force Data LO 00 (FF 00=ON)
Error Check (CRC) -
Table 7.23 Query
Response
The normal response is an echo of the query, which is
returned after the coil state has been forced.
Field Name Example (HEX)
Follower 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) -
Table 7.24 Response
RS-485 Installation and Set... Design Guide
100 Danfoss A/S © Rev. 2014-01-14 All rights reserved. MG18C522
77

Danfoss VLT HVAC Basic Drive FC 101 Specifications

General

Brand	Danfoss
Model	VLT HVAC Basic Drive FC 101
Category	DC Drives
Language	English