WEG MVW3000 A0040 V023, User Manual

Page: 103 / 125

MVW3000 | 9-15
9
Communication Networks
MVW3000 | 9-15
Table 9.7: ASCII characters used in protocol
ASCII
CODE DEC HEX
0 48 30
1 49 31
2 50 32
3 51 33
4 52 34
5 53 35
6 54 36
7 55 37
8 56 38
9 57 39
= 61 3D
STX 02 02
ETX 03 03
EOT 04 04
ENQ 05 05
ACK 06 06
NAK 21 15
The connection between the network nodes is performed through a pair of wires. The signal levels are according
to RS-485 EIA STANDARD, with differential receivers and transmitters. Expansion boards EBA.01, EBA.02 or
EBB.01 (refer to
Item 7.2.1 EBA (I/O Expansion Board A) on page 7-5 and the Item 7.2.2 EBB (I/O Expansion
Board B) on page 7-9 ).
When the master does only have a RS-232 interface, then a RS232/RS485 converter must be used.
RS-232
With the RS-232 interface the connection of one master to one slave is possible (point-to-point). Data can be
exchanged in a bidirectional way, but not simultaneously (HALF DUPLEX).
The logic levels follow the RS-232 EIA STANDARD, which determines the use of unbalanced signaling. In the
present case, one wire is used for transmission (TX), other for reception (RX) and another for ground (0 V). This
configuration is the minimal “3-wire” RS-232 connection (3-wire economy model).
Note: refer to the Item 9.2.4 RS-232 and RS-485 Physical Connection on page 9-23 which describes the
physical connection.
9.2.1 Protocol Definitions
Used Terms
„
Parameters: are those existent in the inverter, whose visualization or modification is possible through the HMI.
„
Variables: are values with specific functions in the inverter and can be read and, in some cases, modified by
the master.
„
Basic Variables: Are those that can only be accessed through the serial communication.