PiXtend V2 -L- Hardware Manual
Due to the ohmic load of the bus or the bus driver through the bias network, no more than
two devices in a bus should have such a bias network.
For serial devices / machines, PiXtend V2 -L- modules can also be ordered without the
560 Ω biasing resistors. Contact us in this regard by e-mail to
.
Manual & automatic mode of the RS485 interface:
The RS485 interface can be operated in two operating modes:
•
Automatic send / receive switching
◦
Jumper in position "A" (default setting - Fig. 84)
◦
Sending / receiving is automatically switched over without having to pay any
attention to the software or the bus driver
◦
Particularly suitable for Modbus RTU
◦
Recommended mode for the RS485 interface on PiXtend
•
Manual send / receive switching
◦
Jumper in position "M" (Fig. 84)
◦
Switching between send / receive must be done by software
◦
Switching via Raspberry Pi GPIO22 (configuration as output)
▪
High level ("1"): send
▪
Low level ("0") or GPIO22 as input: Receive
◦
In some applications it may make sense to send and receive data on the bus via
software
◦
Only recommended for advanced users with special requirements
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Figure 84: Jumper for send / receive switching of
the RS485 interface
