UPS System: HIPULSE E
Communication System Manual
Electrical installation (Modbus/Jbus Interface)
(04/07)
Page 3-5
3.1.2 Multipoint RS-485 connection
To obtain a multipoint RS-485 serial line connection composed of 1 to 32 UPSs, all the devices connected with the
Modbus network must be connected with one another in parallel.
In this case, in addition to the connection of the Operator Logic X4 with the Modbus network described above, X5 must
be used for an additional connection with a cable to provide output to the logic of the other units (refer to Figure 3-6).
The connection must connect pin 1 of X5 output from one UPS with pin 1 of the X4 input of the next UPS, and so on
for the remaining pins.
The signals shown in Table 3-1 will be present in these wires.
Note: In a configuration with an external MSS cabinet, make a connection with a multi-point RS-485 serial line as
shown in Figure 3-6, replacing the UPS 1 connection with the MSS and following the connections for the number of
modules in the system. The MSS Operator Logic board will become P/N 4550008I.
Figure 3-5 Multipoint RS-485 connection
The connection between UPS modules should be made using a two-wire shielded cable with very thick copper braiding
in which the shield forms a third constraining wire (COM) is COMPULSORY. The wire must have a section of 0.25
mm
2
. The length of each cable will depend on the position of the machines in the installation; the total length should not
exceed 1 km.
The RS-485 connection cable must finish at each end with a jumper inserted in the Operator Logic board at position
X 25 1-2; in the example, this must be done on module 4 and on the initial connection at the start of the Modbus
network; the jumper must not be inserted on modules 1, 2, and 3.
There may be electrical problems with the terminal if interface converters purchased on the market are used; this will
not result in incorrect communications. The problem may be solved by connecting up an additional terminal resistance
of adequate size to restore the impedance characteristic of a 120 OHM resistance. The value to be added depends on the
terminal resistance already present.
The impedance of the double wire must be 120 OHMS, in accordance with the RS485 standard.
Warning
Assign a different identification number to each device in a multipoint connection for programming of ID in the
Operator Control Panel menu. (see Section 4.1.1)
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