KEP MMI-1500 Installation & Operation Manual page 19

2.4.5 HMI to HMI Connections
The HMI supports a master - slave communications. One HMI is connected directly to the PLC and configured as the
Master. All the other HMIs are connected in series to it and are configured as Slaves. In theory there is no limitation to the
number of HMIs on a chain, however response time gradually decreases when more than three HMIs are linked together.
The HMI are configured with the EasyBuilder software to be the Master or a Slave.
Wiring between two HMIs
Case 1: Slave to Master, connecting PLC[RS232] directly to PC[RS-232]/PLC[RS485] combination port.
Connect to SLAVE HMI PLC[RS-232] port
Cable has D-SUB Male end
2 TxD
3 RxD
5 GND
Case 2: Slave to Master, connecting PLC[RS232] to PC side of split download cable (MT5_PC) with use of Male to Male Null
Modem cable.
Connect to SLAVE HMI PLC[RS-232] port
Cable has D-SUB Male end
2 TxD
3 RxD
5 GND
Case 3: Ethernet Connections: Units equipped with the Ethernet port can be connected via Ethernet to a Master and Slaves
using standard 10T Ethernet cables. Slave to Master, connect the Ethernet ports with a standard (Category 5) Ethernet 10T
crossover cable (RJ-45 to RJ45). On the other hand, use standard cables with routing passing through Hubs and Servers as
needed.
Connecting a Master directly to a Slave using 10T Crossover cable
Master
Connecting a Master through a Hub to Slaves
Slave
Connect to MASTER HMI PC[RS-232] port
Cable has D-SUB Female end
8 RxD
7 TxD
5 GND
Shield Earth Ground
Connect to MT5_PC to MASTER HMI PC[RS-232] port
Cable has D-SUB Male end
3 RxD
2 TxD
5 GND
Shield Earth Ground
Hub
11
Slave
Slave
Master