Proface LT3300 - 5.7 All-in-One HMI" - Manual (Page 48)

Chapter 2 Specifications
2-21
2.2.3 Interface Specifications
This section describes the specifications of each interface of the LT Series unit.
• The LT unit's serial Interface is not isolated. When the host (PLC) unit is also not
isolated, be sure to connect the #5 SG (Signal Ground) terminal to reduce the risk of
damaging the RS232C/RS422/RS485 circuit.
• In the LT unit, SG (signal ground) and FG (frame ground) are connected internally.
When connecting an external device to the LT using the SG terminal, be sure to
check that no short-circuit loop is created when you setup the system.
• When isolation is necessary, you can use the RS232C isolation unit (CA3-ISO232-01) on
COM1.