Master-Slave Configuration - KEP MMI-1500 Installation & Operation Manual

Ethernet IP settings: These settings are used whenever Ethernet communications is selected for HMI to MMI or MMI to
PLC connections. A working knowledge of TCP/IP networking and terminology is necessary to implement Ethernet
connections.
HMI Local IP address: These fields are the IP address of the HMI unit.
Server IP address: The IP address of the PLC or Slave MMI.
Subnetwork Mask: The mask for the network where the HMI and PLC or Slave are located.
Default Route IP address: This is used for HMI to PLC communications and refers to network server IP settings.
PLC time out constant (sec): This setting determines how long the HMI waits for a response from the PLC before retry.
The range is from 3.0 to 25.5 seconds. This setting is important when the PLC is normally slow to respond or if several
MMI's are linked to one PLC.
PLC block pack: Used to determine how the unit communicates to the controller. By increasing this number, larger blocks of
registers can be fetched from the controller. In some cases, this speeds the update of information on the display. Hint: When
creating a display, it is advised that consecutive registers be used whenever possible.
Note: Communication disconnection handling process
Two conditions cause PLC-HMI communications problems.
The PLC does not respond
The PLC gives an error code response
If the HMI detects communication problems, it responds according to the state of local bit LB9055.
Bit is OFF, 0: Abort: Any command to write data to the PLC is deleted.
Bit is ON, 1: Retry: Keeps on writing command to the PLC.

15.2 Master-Slave Configuration

The HMI supports a master - slave communications. One HMI is connected directly to the PLC and configured as the
Master. All the other MMIs are connected in series to it and are configured as Slaves. In theory there is no limitation to the
number of MMIs on a chain, however response time gradually decreases when more than three MMIs are linked together.
The HMI are configured with the EasyBuilder software to be the Master or a Slave.
Serial Linking is accomplished by connecting the PLC [RS232] port of the slave to the RS232 side of the PLC/PC 232/485
connector of the master or successive unit. Ethernet linking is via crossover cable or through a hub with standard Ethernet
10BaseT cabling.
Serial wiring between two MMIs
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