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MSR128LUS/MSR128LUV USERS MANUAL EM-7375 Rev.2
2.2
CONNECTING TO THE PC
The 53U modules are connected to the PC either via a COM port or via a LAN port. Using both ports at once is Not
Possible.
COM Port:
The MSR128LU communicates with the 53U using Modbus RTU Protocol via RS-232C as physi-
cal layer. Insert Model R2K-1 RS-232C/RS-485 Converter close to the PC.
LAN Port:
The MSR128LU communicates with the 53U using Modbus TCP/IP Protocol via Ethernet as physical
layer. The 53U, Modbus RTU modules are interfaced via Model 72EM(2)-M4 Communication
Adaptor.
2.2.1
MODBUS RTU
As shown in Figure 2.2.1a, the 53U module is connected to PC’s COM port (COM1 through COM5) via the RS-232C/
RS-485 Converter (model: R2K-1).
Connect the 53U to the R2K-1 with a RS-485 twisted pair cable. Connect the R2K-1 to the PC with a straight RS-
232C cable with 9-pin D-sub connectors.
When more than one 53U module are to be monitored, connect these modules with RS-485 twisted pair cables.
Figure 2.2.1a: System configuration example, Modbus RTU.
Detail of Modbus wire configuration is as shown in Figure 2.2.1b.
Figure 2.2.1b: Modbus wiring detail with the R2K-1.
RS-485 (Modbus RTU)
Multi Power Monitor
(model: 53U)
RS-232C
RS-232C/RS-485
Converter
(model: R2K-1 or LK1)
AX
IN
AX
IN
AX
IN
Max. 31 nodes
R2K-1
T1
T2
T3
T4
53U
T1
T2
T3
T4
T1
T2
T3
T4
53U
CONNECTOR
RS-232C
RS-485
*
1
*
1
*
1. Internal terminating resistor is used when the device is at the end of a transmission line.
*
2. Install shield cables to all sections and ground them at single point.
*
2
FG
RS-485
