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Serial Gateway Section 6-6
• Without routing tables that treat serial communications path as a net-
work: Unit address of serial port.
• Remote destination node address (DA1)
• With routing tables that treat serial communications path as a network:
Unit number for Host Link incremented by 1 (1 to 32)
• Without routing tables that treat serial communications path as a net-
work: Unit number for Host Link incremented by 1 (1 to 32)
• Remote destination unit address (DA2)
Any unit address except that for the serial port (The destination for the
FINS message must not be the serial port of the Board/Unit.)
• FINS command code: Any
(2) When creating Host Link FINS command frames using the CMND(490)
instruction, always set the unit number for Host Link incremented by one
(1 to 32) for the remote destination (send destination) node address
(word C+3, bits 08 to 15 of the CMND(490) instruction). Do not set the
unit number of the actual Host Link slave (0 to 31). Using the Host Link
unit number without incrementing by one will access the PLC with the en-
tered Host Link unit number less one.
For example, specify the remote PLC with Host Link unit number 2 by en-
tering 3 for the remote destination node address. If 2 is entered, the PLC
with Host Link unit number 1 will be accessed.
To access a PLC on a Host Link FINS network using the Serial Gateway
from CX-Programmer, however, enter the actual Host Link unit number,
without incrementing by one. (Select Change PLC, click the Display Se-
rial Gateway Guide Button, and set unit number in the Host Link
SYSWAY Settings field of the Serial Gateway Guide Dialog Box.
(3) The contents of the FINS command enclosed by the Host Link header
and terminator is as follows:
@+Host Link unit number+Host Link header FA+FINS header+FINS
command+Text+FCS+*+CR
6-6 Serial Gateway
6-6-1 Serial Gateway Execution Timing for Protocol Macros
The execution timing for the Serial Gateway during execution of protocol mac-
ros is described here. The operation when the FINS command is received
with the Serial Gateway enabled during protocol macro mode is as follows:
• Next step contains the RECEIVE command: Priority is given to the
RECEIVE command, and the Serial Gateway is executed in the next step.
(See note 1).
• Next step contains any command except the RECEIVE command (SEND,
SEND&RECV, WAIT, FLUSH, OPEN, or CLOSE): Priority is given to the
Serial Gateway, for which conversion, transmission, and response recep-
tion processing is executed using interrupts between steps (see note 2).
Note (1) The reception buffer is cleared during transfer processing using the Serial
Gateway. Therefore, when the FINS command is received, and the com-
mand in the following step is the RECEIVE command, the RECEIVE
command takes priority over the Serial Gateway.
(2) The Serial Gateway is executed using interrupts between steps. The in-
terrupts are not executed within a step. (Therefore, the Serial Gateway is
never executed after the SEND command in a SEND&RECV command.)
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