Specifications

Table Of Contents
Third-Party and Building Management Interfaces
25
5.3 BMS Front-End Interfacing to Liebert Equipment by EIA-485 Modbus
Modbus is an industry standard means of communicating between systems from different vendors. A
SiteScan Web system using Modbus allows a Third Party to request information from a SiteLink,
With SiteScan Web, single or multiple SiteLinks can communicate to other systems using Modbus on
either Port A or Port B.
Both ports send out Modbus information. They differ in that Port A is configurable for RS-232 or two-
or four-wire RS-485 media access. Port B is DB-9 and RS-232 only.
5.3.1 Port A—RS-485 Modbus
When configured for RS-485, this allows Port A to be daisy-chained with multiple SiteLinks. In this
example, both the SiteLinks and the third-party device use a five-screw terminal to make the wiring
connection. When using RS-485 each SiteLink or the third-party equipment is between 1250 and
4,000 ft. (381-1219m) away depending on the baud rate being used. Make this connection with
shielded or unshielded twisted pair wiring.
Figure 12 Modbus on Port A—RS-485
Table 14 Bill of materials: Port A—RS-485 Modbus
Qty. Mktg. P/N Description
3 SITELINK-4-M SiteLink-4-M (4 Liebert IGM interfaces)
3 XFMR24 Transformers for 120/24VAC module power supply
Note: The bill of materials does not include LGS startup part numbers. Most LGS startup part
numbers are added automatically when ordering.
Third
Party
Network
RS-485