IDEC MicroSmart - Manual (Page 293)

17: U SER C OMMUNICATION I NSTRUCTIONS
« FC4A M ICRO S MART U SER ’ S M ANUAL » 17-15
RXD1 (Receive 1)
Applicable CPU Modules
RXD2 (Receive 2)
Applicable CPU Modules
Valid Operands
For the valid operand number range, see pages 6-1 and 6-2.
▲ Internal relays M0 through M1277 can be designated as D1. Special internal relays cannot be designated as D1.
Receive format designated by operand S1 can be a maximum of 200 bytes.
When data receive is complete, an output or internal relay, designated by operand D1, is turned on.
Destination 2 occupies two consecutive data registers starting with the operand designated by D2. The receive status data
register, D0 through D1298 or D2000 through D7998, stores the status of data receive and error code. The next data regis-
ter stores the byte count of received data. The same data registers can not be used as transmit status registers for TXD1/
TXD2 instructions and receive status registers for RXD1/RXD2 instructions.
While RXD1/RXD2 instructions are ready for receiving data after a receive format is complete, turning on the user com-
munication receive instruction cancel flag M8022 or M8023 cancels all RXD1/RXD2 instructions.
The RXD1/RXD2 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 the RXD Instruction
•
The MicroSmar t can execute a maximum of five RXD1 and five RXD2 instructions that have a star t delimiter at the same
time. If a star t delimiter is not programmed in RXD1/RXD2 instructions, the MicroSmar t can execute only one RXD1 and
one RXD2 instructions at a time. If the star t input for a RXD1/RXD2 instruction is turned on while another RXD1/RXD2
instruction without a star t delimiter is executed, a user communication error occurs.
•
Since RXD instructions are executed in each scan while input is on, a pulse input from a SOTU or SOTD instruction should
be used as required.
•
Once the input to the RXD instruction is turned on, the RXD is activated and ready for receiving incoming communication
even after the input is turned off. When the RXD completes data receiving, the RXD is deactivated if the input to the RXD is
off. Or, if the input is on, the RXD is made ready for receiving another communication. M8022/M8023 deactivate all RXD
instructions waiting for incoming communication.
FC4A-C10R2/C FC4A-C16R2/C FC4A-C24R2/C FC4A-D20K3/S3 FC4A-D20RK1/RS1 & FC4A-D40K3/S3
X X X X X
FC4A-C10R2/C FC4A-C16R2/C FC4A-C24R2/C FC4A-D20K3/S3 FC4A-D20RK1/RS1 & FC4A-D40K3/S3
— X X X X
Operand Function I Q M R T C D Constant Repeat
S1 (Source 1) Receive format — — — — — — X X —
D1 (Destination 1) Receive completion output — X
▲ — — — —
— —
D2 (Destination 2) Receive status — — — — — — X — —
When input is on, data received through por t 1 from a remote terminal is
conver ted and stored in data registers according to the receive format
designated by S1.
RXD
1 S1
*****
D1
*****
D2
*****
When input is on, data received through por t 2 from a remote terminal is
conver ted and stored in data registers according to the receive format
designated by S1.
RXD
2 S1
*****
D1
*****
D2
*****