Chapter 9 Slave Mode
9-1
Chapter 9
Slave Mode
In addition to having the functions as a master/scanner that can perform I/O communication with one or more
slaves, the EH-RMD supports the slave mode in which it can perform I/O communication with other EH-RMD
modules and/or master modules made by other companies.
It is possible to use one EH-RMD as a master at one time and in the slave mode at another time.
9.1 Overview
This section shows an example of a system configuration where the EH-RMD is used in the slave mode.
Figure 9.1 shows an example of a system configuration where the EH-RMD is used as the master and performs I/O
communication with the slaves, including an EH-RMD operating as a slave.
The I/O on PLC2 is controlled by the CPU module on PLC2. PLC1 exchanges the necessary information with PLC2
via the EH-RMD modules (both master and slave).
The I/O data size of the EH-RMD in the slave mode is set in the configurator.
Figure 9.2 illustrates a system example configured for the purpose of sharing information of each PLC by making
each EH-RMD run as master and/or slave.
In DeviceNet, a slave device cannot communicate with multiple masters. Thus, unlike a common CPU link system,
it cannot send data to multiple PLCs.
Figures 9.3 and 9.4 show how to use the link area of the H series CPU link module and the link area in a link
system constructed by means of EH-RMD modules.
Figure 9.1 System configuration example 1 illustrating the use of the slave mode
EH-RMD (slave)
PLC2
HITACHI RXD16D
MS
NS
HITACHI RXD16D
MS
NS
EH-RMD (master)
PLC1
PO WER
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EH-IOCD
Figure 9.2 System configuration example 2 illustrating the use of the slave mode
PLC2 PLC4
EH-RMD (master) or a
master module made by
another manufacturer
PLC1
EH-RMD (slave)
EH-RMD (slave)
PLC3
EH-RMD (master & slave)
HITACHI RXD16D
MS
NS
HITACHI RXD16D
MS
NS
EH-150 CPU
EH-150 CPU