Getting Started: I-8437-80/8837-80/8417/8817, Jul 2020 V2.0 51
3.3
Connecting PC to I-8417/8817’s COM2
If the user wants to connect the PC to the COM2 of I-8xx7, an I-7520R (RS-232/RS-485 converter)
is required. The maximum valid distance between I-7520R and the PAC is 1, 200 meters (4, 000
feet). The distance is related to the baud rate that means the lower baud rate is set, the longer
transmission distance can be.
3.4
Connecting PC to Several I-8417/8817’s COM2
The benefit of using the COM2 port (RS-485) is that you can use one PC to connect several PACs
to form an RS-485 network. In this way, the PC can download ISaGRAF project to each PAC via
the RS-485 network. Up to 255 I-8xx7 can be connected each other. We do not recommend
connecting so many PACs if not necessary.
To create an RS-485 network you must first insure that each I-8417/8817 PAC has a unique
NET-ID address, and each of the PACs link the
“
DATA+
”
to the
“
DATA+
”
signal and the
“
DATA-
”
to
the
“
DATA-
”
signal.
If the RS-485 communication is unstable, it is recommended to wire a terminal resistor (try
220
, 110
, or 330
, in order) on COM2 on the first and the last PACs
By default, the pull-high (JP1) and pull-low (JP2)
resistor inside the PAC are set to “Disable” (i.e.,
Pin2-3). When using I-8417/8817 as a Modbus
Master, you need to set both the JP1 and JP2 to
“Enable” (i.e., Pin1-2).
(Enable
)