___________________________________________________________________________________
WRMnano User Manual page
6
/
18
respond on Primary address 253 (0xFD).
The response from WRMnano of the standard short-frame readout command is
something like this:
0x68 L
L
0x68 C
A
CI
DATA
CHK
0x16
where:
0x68 and 0x16 are start/stop bytes
L is length of the telegram according to EN 13757-3
C, A, CI are respectively C-field, primary address and CI-field
CHK is checksum of the telegram, according to EN 13757-3
DATA is user data, including header and the payload
HEADER (12 bytes fixed length)
DATA PAYLOAD
Header is 12-byte fixed length, then the data comprises of the wireless
message and several option fields, if enabled. These fields may include timestamp of
the message and RSSI of this particular message.
Header format is as follows
ID
MFR
Version
Medium
Access No
Status
Signature
4-byte BCD 2 byte
1 byte
1 byte
1 byte
1 byte
2 byte
ID
is the 8-digit ID of the wireless m-bus device
MFR
is the manufacturer of the device, encoded in 3 letters, copied from Wireless m-bus
telegram
Version
– this is the firmware revision of the device, copied from Wireless m-bus telegram
Medium
– medium of the device, copied from Wireless m-bus telegram
Access No
– transmit count of the device, rollover @ 255; copied from Wireless m-bus
telegram
Status
– Status, copied from Wireless m-bus telegram
Signature
– signature, copied from wireless m-bus telegram, with one exception – if
decryption is enabled and the message is decrypted, all encryption fields are deleted to notify
the master that the message is no longer encrypted.
Data payload is formatted as follows:
Wireless m-bus message
Timestamp (option field)
RSSI (option field)
Variable length
6 bytes
2 bytes
Wireless m-bus message is copied without any changes, as received from the meter.
Timestamp is added only if enabled, this is the time & date of the last message
reception from the device with this selected ID. The clock of the timestamp is the
internal clock of the WRMnano. The timestamp format is as follows:
0x04
0x6D
TIMEPOINT
DIF
VIF
Standard 4-byte time&date m-bus format, data type F
