10: U
SER
C
OMMUNICATION
I
NSTRUCTIONS
10-6
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
TXD (Transmit)
When input is on, data designated by S1 is converted into a specified format
and transmitted from port 1 through port 7 to a remote terminal with an
RS232C port.
TXD2 to TXD7 can be used to communicate with an RS485 remote terminal on
port 2 to port 7.
TXD3 through TXD7 are available on upgraded CPU modules with system pro-
gram version 110 or higher. For details about expansion RS232C/RS485 com-
munication on port 3 to port 7, see page 25-1 (Advanced Vol.).
TXD
*
S1
*****
D1
*****
D2
*****
Applicable CPU Modules
FC5A-C10R2/C/D
FC5A-C16R2/C/D
FC5A-C24R2D
FC5A-C24R2/C
FC5A-D16RK1/RS1
FC5A-D32K3/S3
FC5A-D12K1E/S1E
TXD1-TXD2
TXD1-TXD2
TXD1-TXD5
TXD1-TXD7
TXD1-TXD7
TXD2-TXD7
Valid Devices
Device
Function
I
Q
M
R
T
C
D
Constant
Repeat
S1 (Source 1)
Transmit data
— — — — — —
X
X
—
D1 (Destination 1)
Transmit completion output
—
X
— — — —
—
—
D2 (Destination 2)
Transmit status register
— — — — — —
X
—
—
For the valid device address range, see pages 6-1 and 6-2.
Internal relays M0 through M2557 can be designated as D1. Special internal relays cannot be designated as D1.
Transmit data designated by device S1 can be a maximum of 200 bytes.
When transmission is complete, an output or internal relay, designated by device D1, is turned on.
Destination 2 occupies two consecutive data registers starting with the device designated by D2. The transmit status data register, D0-
D1998, D2000-D7998, or D10000-D49998, stores the status of transmission and error code. The next data register stores the byte
count of transmitted data. The same data registers can not be used as transmit status registers for TXD1 through TXD7 instructions and
receive status registers for RXD1 through RXD7 instructions.
The TXD instructions cannot be used in an interrupt program. If used, a user program execution error will result, turning on special
internal relay M8004 and the ERR LED on the CPU module.
Precautions for Programming TXD Instruction
The MicroSmart has five formatting areas each for executing TXD1 through TXD7 instructions, so five instructions each of TXD1
through TXD7 can be processed at the same time. If inputs to more than five of the same TXD instruction are turned on at the same
time, an error code is set to the transmit status data register, designated by device D2, in the excessive TXD instructions that cannot
be executed.
If the input for a TXD instruction is turned on while another TXD instruction is executed, the subsequent TXD instruction is executed
2 scan times after the preceding TXD instruction is completed.
Since TXD instructions are executed in each scan while input is on, a pulse input from a SOTU or SOTD instruction should be used as
required.
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