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7. Message transmission
7.1 Message transmission
The message transmission is text transmission to be performed communication on request. This
transmission is following two protocol.
Computer link protocol
PC link protocol
7.2 Computer link protocol
The host machine can communicate to a T2N/T3H on the S20LP using the computer link
protocol. Since this function executes the station and firmware, there is no need to create pecial
user programs for the T2N/T3H using the slave station.
The host machine used this protocol can execute following process for the T2N/T3H.
Upload or download user programs.
Status observation (reading out RUN/HALT/ERROR status).
Read or write register/device data.
Execute control commands.
The computer link protocol cannot execute following process.
T2N/T3H is Down mode.
A S20LP-station except for ONLINE and STANDBY mode.
7.3 PC link protocol
This section presents an overview of the SEND and RECV instructions, which are the
instructions that are used to control the S20LP-station from T2N/T3H user programs. S20LP-
station transmission control (PC link protocol transmission) is performed solely using the SEND
and RECV instructions. See the individual items for details on the actual requests sent to the
S20LP.
The PC link protocol allows one T2N/T3H on network to write or read register data to another
T2N/T3H.
When this function is used on the PC link slave station, there is no need to create
programs for the T2N/T3H using the slave station.
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special user
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