Lufft VENTUS-UMB - Communication in ASCII Protocol

Operating Manual V25/09.2019 Ventus / Ventus-X / V200A
Chapter 20 Appendix 43
20.4 Communication in ASCII Protocol
Note: UMB-ASCII protocol is not recommended for new projects. New features will not be
implemented for this protocol for devices newer than device version 36.
Text-based communication with devices is possible using ASCII protocol.
To do this, in the device configuration, interface settings, the protocol mode must be set to
ASCII (see page 25).
ASCII protocol is network-compatible and serves exclusively for online data requests. The
device will not respond to incomprehensible ASCII commands.
Note: The use of binary protocol is recommended for lengthy transmission routes (e.g. network,
GPRS/UMTS), as ASCII protocol is unable to detect transmission errors (not CRC-secured).
Note: TLS channels are not available in ASCII protocol.
20.4.1 Structure
An ASCII command is introduced by the ‘&’ character and completed by the CR (0Dh) sign.
There is a space character (20h) between the individual blocks in each case; this is represented
by an underscore character ‘_’. Characters that represent an ASCII value are in ordinary
inverted commas.
20.4.2 Summary of ASCII Commands
Command
Function
BC
AZ
M
Online data request
l
X
Switches to binary protocol
k
R
Triggers software reset

k
D
Software reset with delay

k
I
Device information
k
These operating instructions describe the online data request only. You can find the description
of the other commands in the UMB protocol.
20.4.3 Online Data Request (M)
Description: By way of this command, a measurement value is requested from a specific
channel.
Request: ‘&’_<ID>
5
_‘M’_<channel>
5
CR
Response: ‘$’_<ID>
5
_‘M’_<channel>
5
_<value>
5
CR
<ID>
5
Device address (5 decimal places with leading zeros)
<channel>
5
Indicates the channel number (5 decimal places with leading zeros)
<value>
5
Measurement value (5 decimal places with leading zeros); a measurement value
standardized to 0 – 65520d. Various error codes are defined from 65521d – 65535d.
Example:
Request: &_32769_M_00100
By way of this request, channel 100 of the device with address 32769 ( Ventus with device ID
001).
Response: $_32769_M_00100_34785
This channel outputs a temperature from –40 to +60°C; this results in the following calculation:
0d corresponds to -50°C
65520d corresponds to +70°C
36789d corresponds to [+70°C – (-50°C)] / 65520 * 34785 +(-50°C) = 13,7°C
Note: TLS channels are not available in ASCII protocol.