Specifications

SIMATIC Instructions
9-184
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
Freeport Initialization
SMB30 and SMB130 configure the communication ports, 0 and 1, respectively, for
Freeport operation and provide selection of baud rate, parity, and number of data
bits. The Freeport control byte(s) description is shown in Table 9-25.
Table 9-25 Special Memory Bytes SMB30 and SMB130
Port 0
Port 1 Description
Format of
SMB30
Format of
SMB130
7
MSB LSB
Freeport mode control byte
ppdbbbmm
0
SM30.6
and
SM30.7
SM130.6
and
SM130.7
pp Parity select
00 = no parity
01 = even parity
10 = no parity
11 = odd parity
SM30.5 SM130.5 d Data bits per character
0 = 8 bits per character
1 = 7 bits per character
SM30.2 to
SM30.4
SM130.2
to
SM130.4
bbb Freeport Baud rate
000 = 38,400 baud
001 = 19,200 baud
010 = 9,600 baud
011 = 4,800 baud
100 = 2,400 baud
101 = 1,200 baud
110 = 600 baud
111 = 300 baud
SM30.0
and
SM30.1
SM130.0
and
SM130.1
mm Protocol selection
00 = Point-to-Point Interface protocol (PPI/slave mode)
01 = Freeport protocol
10 = PPI/master mode
11 = Reserved (defaults to PPI/slave mode)
Note: One stop bit is generated for all configurations.
Using the XMT Instruction to Transmit Data
The XMT instruction lets you send a buffer of one or more characters, up to a
maximum of 255. An interrupt is generated (interrupt event 9 for port 0 and
interrupt event 26 for port 1) after the last character of the buffer is sent, if an
interrupt routine is attached to the transmit complete event. You can make
transmissions without using interrupts (for example, sending a message to a
printer) by monitoring SM4.5 or SM4.6 to signal when transmission is complete.