IDEC FC6A-C16K1CE Communications Manual page 86

5: U C
SER OMMUNICATION
RXD (Receive)
RXD
* *****
Valid Devices
Device
S1 (Source 1)
D1 (Destination 1)
D2 (Destination 2)
For valid device address ranges, see Chapter 2 "Device Addresses" in the "FC6A Series MicroSmart LAD Programming Manual".
*1 Internal relays M0 through M7997 or M10000 through M17497 can be designated as D1. Special internal relays cannot be designated as D1.
*2 Special data registers cannot be used.
Receive format designated by device S1 can be a maximum of 1,536 bytes.
When data receive 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 receive status data register, D0000-D7998 or
D10000-D55998, stores the status of data receive and error code. The next data register stores the byte count of received data. The same data
registers can not be used as transmit status registers for TXD1 through TXD3 instructions and receive status registers for RXD1 through RXD3
instructions.
The RXD 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 FC6A Series MicroSmart. For details about the user program execution errors, see Chapter 3 "User Program
Execution Errors" in the "FC6A Series MicroSmart LAD Programming Manual".
Precautions for Programming the RXD Instruction
The FC6A Series MicroSmart can execute a maximum of five instructions each of RXD1 through RXD3 that have a start delimiter at the same
•
time. If a start delimiter is not programmed in RXD1 through RXD3 instructions, the FC6A Series MicroSmart can execute only one instruction
each of RXD1 through RXD3 at a time. If the start input for a RXD1 through RXD3 instruction is turned on while another RXD1 through RXD3
instruction, without a start 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.
•
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. Special internal relays are available to deactivate all RXD instructions waiting for incoming
communication. For user communication receive instruction cancel flags, see "User Communication Receive Instruction Cancel Flag" on page 5-22.
User Communication Receive Instruction Dialog Box in WindLDR
Selections and Devices in Receive Instruction Dialog Box
TXD
Type
RXD
Port No. Port 1 - Port 3
S1 Source 1
D1 Destination 1
D2 Destination 2
5-10
I
NSTRUCTIONS
S1 D1 D2
***** *****
Function
Receive format
Receive completion output
Receive status
Transmit instruction
Receive instruction
Receive user communication to port 1 (RXD1) through port 3 (RXD3)
Enter the receive format in this area.
The receive format can include a start delimiter, data register to store incoming data, constants, end
delimiter, BCC, and skip.
Receive completion output can be an output or internal relay.
Receive status register can be data register D0000-D7998 or D10000-D55998.
The next data register stores the byte count of received data.
FC6A S M S A
ERIES ICRO MART
When input is on, data from an RS232C/RS485 remote terminal received by port 1
through port 3 is converted and stored in data registers according to the receive
format assigned by S1.
I Q
— —
— X
— —
- -O T C
LL IN NE YPE OMMUNICATION
M R T C D Constant
— — — — X
*1
X — — — —
*2
— — — — X
M FC9Y-B1730
ANUAL
Repeat
X —
— —
— —