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Communications Timing Section 4-4
The operation of Host Link communications is not affected by a protocol data
error.
Port Setting Status The settings in the Setup Area for the following items will be stored: Serial
communications mode, baud rate, start bits, data length, stop bits, parity,
ports, terminating resistance, setup error, and port operating/stopped status.
The port operating/stopped status will always be 1 for Host Link mode.
Communications Status The flow control and buffer status is stored. These bits are cleared at startup
or when a port is restarted using STUP(237) or a Port Settings Change Bit
(Auxiliary Area).
Transmission Control
Signal Status
The status of the following transmission control signals is stored: ER signal,
DTR signal, CTS signal, and RTS signal. 1: High, 0: Low
Transmission Error Status The Transmission Error Flag (bit 15) will turn ON if any of the following flags
turn ON: Overrun Error (bit 04), Framing Error (bit 03), or Parity Error (bit 02).
4-4 Communications Timing
This section describes the timing of sending commands and controlling com-
munications in the Host Link mode.
4-4-1 Simultaneous Commands and Communications Ports
The CS/CJ-series CPU Units provide eight logical ports that can be used
when executing SEND(090), RECV(098), and CMND(490). Therefore, up to
eight commands can be executed for one physical port during any one cycle.
The maximum number of messages, however, that can be sent or received in
one CPU Bus Unit service time is two messages from the CPU Unit to the
Board or Unit and two messages from the Board or Unit to the CPU Unit.
Note 1. If more than eight communications instructions are being used, then exclu-
sive control must be performed to make sure that not more than eight are
executed at the same time. Refer to descriptions of network communica-
tions instructions in the CS/CJ-series Communications Commands Refer-
ence Manual (W342).
2. The same communications port numbers are used by both the communi-
cations instructions (SEND(090), RECV(098), and CMND(490)) and the
PROTOCOL MACRO instruction (PMCR(260)). The same port number
cannot be used by more than one of these instructions at the same time.
Board or Unit Logical port CPU Unit
Instruction 1
Instruction 2
Instruction 3
Instruction 4
Instruction 5
Instruction 6
Instruction 7
Instruction 8
One port must be specified for each instruction.
5
1
6
3
7
2
0
4
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