Communication Boards Connection - Mettler Toledo IND256x Installationshandbuch

2.7.

Communication Boards Connection

2.7.1. Serial Port (COM1)
The COM1 port includes connections for an intrinsically safe serial device. Figure 2-10 indicates the
COM1 port connector. The cable length of this connection is limited to 10m (33 ft.).
An example of connecting to an RS-232 device in the safe area through a Zener diode barrier is
shown in Figure 2-11. Refer to the entity approval values of COM1 when selecting a barrier. Note
that seals and other protective devices will also be required to meet hazardous area wiring codes.
A barrier that has been tested for correct operation with the IND256x, and can be connected directly
to COM1, is:
•
2-8 METTLER TOLEDO IND256x Weighing Terminal Installation Manual
Figure 2-11: Sample RS-232 Connection
MTL7761Pac (IECEx and ATEX approvals)
Figure 2-9: Load Cell Termination
IND256x
J1- 1
J1 - 2
J1 - 3
Figure 2-10: COM1 Port Signals
Signal
TxD–send data
RxD–receive data
GND–logic ground
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