Danfoss MCD3000 Series Manual page 14

Master command to slave.
ASCII STX [command]
or 02h [c1]h [c2]h [c3]h
[command] = 3 byte ASCII command (or request)
selected from the tables below.
LRC = Longitudinal Redundancy Check.
Slave response if Command and LRC correct
ASCII ACK
or 06h
Slave response if Command and LRC incorrect
ASCII NAK
or 15h
Slave response of Read request correct and LRC
correct.
ASCII STX [data]
or 02h [d3]h [d2]h [d1]h [d0]h
Slave response if Read request or LRC invalid.
ASCII NAK
or 15h
Each command, status or data request is a 3 byte
string as detailed below. Invalid command/request
strings cause the MCD3000 to respond with a NAK
(15h).
Command ASCII
Start B10
Stop B12
Reset B14
Coast to stop B16
Status Read ASCII
Status C10
Status_1 C12
Trip C14
Version C16
14
LRC ETX
[LRC1]h [LRC2]h 03h
LRC ETX
[LRC1]h [LRC2]h 03h
Comment
Initiates a start.
Initiates a stop
Resets a trip state
Initiates an immediate
removal of voltage from the
motor. Any soft stop or
D.C.Brake settings are
ignored.
Comment
Requests the configuration
status of the MCD3000.
Requests the operational
status of the MCD3000.
Requests the trip status of
the MCD3000.
RS485 protocol version
number.
MCD3000 Series
Data Read ASCII
Current D10
Temperature D12
Each command string sent to and from the MCD3000
includes a check sum. The form used is the
Longitudinal Redundancy Check (LRC) in ASCII hex.
This is an 8-bit binary number represented and
transmitted as two ASCII hexadecimal characters.
To calculate LRC:
1. Sum all ASCII bytes
2. Mod 256
3. 2's complement
4. ASCII convert
For example Command String (Start);
ASCII STX B 1
or 02h 42h 31h
ASCII Hex Binary
STX 02h 0000 0010
B 42h 0100 0010
1 31h 0011 0001
0 30h 0011 0000
A5h 1010 0101
A5h 1010 0101
5Ah 0101 1010
01h 0101 1011
5Bh 0101 1011
ASCII 5 B
or 35h 42h
The complete command string becomes
ASCII STX B 1
or 02h 42h 31h
To verify a received message containing an LRC;
1. Convert last two bytes of message from ASCII to
binary.
nd
2. Left shift 2 to last byte 4 bits.
3. Add to last byte to get binary LRC.
MG.15.A2.22 – VLT is a registered Danfoss trademark
Comment
Requests motor current.
The data is 4 byte decimal
ASCII. Minimum value
0000, Maximum value
9999 Amps.
Requests the calculated
value of the motor thermal
model as a % of Motor
Thermal Capacity. The
data is 4 byte decimal
ASCII. Minimium value
0000%. Trip point 0105%.
0
30h
SUM (1)
MOD 256 (2)
1's COMPLEMENT
+ 1 =
2's COMPLEMENT (3)
ASCII CONVERT (4)
LRC CHECKSUM
0 5 B ETX
30h 35h 42h 03h