Renu Electronics GWY-00, User Manual, Page: 19 / 105

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4.1 Gateway Modes
Gateway has two modes of operation: Master-Master and Master-Slave. Before explaining these modes
further Master and Slave concept should be explained.
Master:
Master is a Device which initiates communication.
Slave:
Slave is Device which processes Master’s query, takes necessary action and responds to the query, if
necessary.
4.1.1 Master-Master configuration
In this mode both Gateway ports (PLC1 & PLC2) are master in nature and devices connected on these ports
are slave. Gateway ports initiate communication when the proper Gateway-Device communication cable is
attached. Data is transferred in blocks. This transfer can either be a continuous process or as per require-
ment. A control word (Section 4.4), present in device on either side, enabled from Gateway Setup Software,
can control the block execution.
When control word is disabled, then block transfer is a continuous process. A block of data is fetched from
one device and transferred to the other device. The amount of data to be transferred (Number of words)
depends on Block definition in “Block Definition Area” in Configuration Software. One block is executed at a
time. A cycle consists of execution of blocks from #1 to #n.
Execution of blocks is performed as follows,
Block #1
Block #2
Block #3
Block #4
Block #n
.
.
.
.
.
When Control word is enabled, it decides which block has to be executed by writing a specific data in the
control word. Please refer to Example 4.1 for description on defining Blocks in Master - Master configuration.