76 Ethernet module User’s Manual
Chapter 5 Computer Link Protocol and the PC Link Protocol Transmission
5
5.4 PC Link Protocol Transmission (Data read)
The T series PC link protocol allows an S controller to read register data from another S
controller/T3H/T2N on the network into its own registers.
As is the case with the computer link protocol, the PC link protocol uses UDP/IP as its
transmission protocol.
The PC link main station uses a UDP socket for message transmission and transmits to
the slave station EN311 message transmission UDP socket. The user program that runs
on the main station is discussed later.
When this function is used on the PC link slave station, the controller simply performs the
following as described in Chapter 4:
• Parameter setup and
• Operating mode control (message transmission permission)
There is no need to create any special user programs on the controller.
Register read request (using the URECV_T instruction)
The register data specified by the remote station is read to the specified register on the
local station.
(1) Request command structure and error status
<Request command>
• Local station register is specified by the input operand P of the URCV_T function
block.
• Transfer register size is specified by the input operand N of the URCV_T function.
Specify in words: 1 to 485 words
T register and C register: 1 to 323 words
Usage Recommendations
• Since UDP/IP does not provide control functions to guarantee communication reliability,
higher level protocols (such as retry) are required.
• No processing is performed if a PC link protocol transmission message is received at any
point other than a message transmission UDP socket.
F0
CMD Destination EN311 module slot number
CMD+1 Command (16#0321)
CMD+2 DRID Remote station register type code
CMD+3 DregNo Remote station register number
CMD+4 TimeCnt Timeout time
CMD+5 D-IP address: The input format is the same as
that for parameter setup
requests.
Remote station IP address
CMD+6
CMD+7 D-UDP PortNo Remote station message
transmission UDP port number
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