Panasonic FP2 User Manual page 13

FP2 Serial Data Unit
Operation of the CD (received line signal detector) signal
The CD (Received line signal detector) signal pin of the serial data unit is connected to
the ER (Data terminal ready) pin on the other side. When the CD (Received line signal
detector) signal of the serial data unit goes on, data reception processing begins, and
when the signal goes off, data reception processing stops.
FP2
SDU
SD RD ERR SD RD ERR AL
COM.1 C OM.2
COM.1(RS232C)
COM.2(RS232C)
Received buffer
When flow control is being carried out in the serial data unit, the control signals CS and
CD should be set to "Valid" in the transmission format settings.
Note
When using two channels (COM1 and COM2) setting the control
signals CS and CD to "Valid", the CS of external device should
be always on.
If the CS is off, the communication service of the other channel
will stop.
End code
With the serial data unit, up to 500 characters can be sent or received at one time. The
series of consecutive data elements (characters) being sent at one time is called a
frame.
An "end code" indicates the end of this frame. If there is no end code, the serial data
unit cannot send or receive data, so always make sure the end code is provided in the
data being transmitted.
FP2
SDU
SD RD ERR SD RD ERR AL
COM.1 COM.2
COM.1(RS232C)
COM.2(RS232C)
With the serial data unit, the end code is set to "C
the factory, but this can be changed to "C
in the transmission format settings.
If "Any code" is selected, the code (1 byte) to be used as the end code should be
registered in address 1001 (COM.1) or 1002 (COM.2) of the shared memory.
CD (Received line
signal detector)
The serial data unit begins reception
processing when the CD signal goes on.
1 frame
Data Data Data
The series of consecutive data being
sent at one time is called a frame.
(H0D)+LF(H0A)", "EXT(H03)", or "Any code"
R
Transmission Speed and Transmission Format
ER (Data terminal ready)
End code
− − − − − − −
(CR)
(H0D)" when the unit is shipped from
R
External
device
External
device
xi