Program instructions
7.3 Communication
S7-200 SMART
178 System Manual, 09/2015, A5E03822230-AC
Transmit and receive (Freeport on RS485/RS232)
You can use the Transmit (XMT) and Receive (RCV) instructions for communication
between a S7-200 SMART CPU and other devices through the CPU serial port(s). Each
S7-200 SMART CPU provides an integrated RS485 port (Port 0). The standard CPUs
additionally support an optional CM01 Signal Board (SB) RS232/RS485 port (Port 1). The
communication protocol must be implemented in the user program.
T
The Transmit instruction (XMT) is used in Freeport mode to transmit data by
means of the communications port(s).
T
The Receive instruction (RCV) initiates or terminates the receive message
function. You must specify a start and an end condition for the Receive box to
operate. Messages received through the specified port (PORT) are stored in
the data buffer (TBL). The first entry in the data buffer specifies the number of
bytes received.
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