Telemetry Module MT-102 User's Manual - BlueNote Communications

This mode was implemented due to requirement of reading from devices operating in M-Bus
protocol, applied mainly for measuring of energy consumption in heating systems. Since MT-
102 module has no capability of direct communication with M-Bus units it is necessary to
connect an external converter to PORT2. The converter RM-120 is one of our products.
7.10. NMEA 0183 mode
NMEA 0183 mode is an extension of Modbus RTU Slave mode with the function of receiving
and interpreting of data in NMEA 0183 format sent by peripheral device attached to PORT2.
Standard NMEA 0183 protocol frames are decoded and stored in module's internal registers
where they are ready for further processing.
This mode was implemented to serve the AIRMAR weather station, but may be used to
communicate with GPS receivers using NMEA 0183 protocol for data exchange.
7.11. FlexSerial mode
In FlexSerial mode, the transmission at PORT 2 is serviced exclusively by a user program
resident in the module. Only standard access to module's resources is possible via GPRS. No
option of sending data frame to PORT 2 while data incoming to PORT2 arrives exclusively to
internal program is available.
Buffer structure
PORT 2 in the program is served by 2 buffers and helps registers placed in holding register's
memory space. Transmission and reception are independent on each other.
The buffers have a length of 512, 16 bit registers, where only low order bytes are used for
transmission. In other words, one 16 bit register stores 1 byte on low order byte. High order
byte remains unused.
Data reception
Configuration for FlexSerial mode uses 2 variables that define the way data stream received
at PORT 2 is converted into data packets available for internal program.
Received data is stored in registers. Registers P2RCV_B1…P2RCV_B512, build the receiving
buffer. Register P2RCV_NO controls data reception.
Data received at PORT 2 is internally buffered in 6kB buffer and put into receiving buffer only
when register P2RCV_NO has "0" value. During data insertion to the buffer the length of
inserted package is recorded into P2RCV_NO register. The user program should process data
from receiving buffer after detecting a non zero value in P2RCV_NO buffer and when done
should set P2RCV_NO to 0 value, thereby initiating loading of next package to buffer.
Received data is always placed at the beginning of the buffer so the first byte of the package
is placed in P2RCV_B1 register.
Furthermore, in binary output space there is P2RCV_err bit that is set high when reception
error occurs. F.e.: receiving buffer overflow, parity, stop bit error. P2RCV_err bit is not
automatically reset so in order to be useful for diagnostic purposes, it has to be reset by the
user program. The state of this bit does not have influence on data reception algorithm and
is only used for received data diagnostic.
Resources
Name Space (address DEC) Description
P2RCV_NO Internal registers (1022) Register controlling reception
P2RCV_B1…513 Internal registers. (1024…1535) Receiving buffer
P2RCV_err Output bits (60) Reception error signaling
Data transmission
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