Horner APG XL7 OCS - Manual (Page 25)

XL7 User Manual
5.4 RS485 Termination
Proper RS485 termination minimizes signal reflections and improves reliability.
Both the MJ2 and MJ3 serial ports allow an internal termination resistor to be placed across pins 1 and 2 by DIP
Switch Setting.
Only the two devices physically located at the endpoints of the RS485 network should be terminated.
5.5 RS485 Biasing
RS485 biasing passively asserts a line-idle state when no device is actively transmitting, which is useful for multi-
drop RS485 networking.
Both the MJ2 and MJ3 serial ports allow internal bias resistors to be switched in, pulling pin 1 up to 3.3V and
pulling pin 2 down to ground. The Set Serial Ports item in the System Menu can be used to enable RS485 biasing.
Also, an
application graphics screen that writes to %SR164 can do the same thing. Setting %SR164.1
enables MJ2 biasing and setting %SR164.2 enables MJ3 biasing.
If biasing is used, it should be enabled in only one of the devices attached to the RS485 network.
5.6 Cscape Programming via Serial Port
The XL7 OCS MJ1 and MJ3 serial ports support CsCAN Programming Protocol. If a PC COM port is
connected to the XL7 OCS MJ1 or MJ3 serial port, Cscape can access the XL7 OCS for programming and
monitoring. Programming can also be done via the CAN port, USB A port or Ethernet.
5.7 Ladder-Controlled Serial Communication
Using Serial Communication function blocks, MJ1, MJ2 and MJ3 serial ports support Generic Modbus
Master and Modbus Slave Protocols. In addition, external modems can be connected and accessed
using Init, Dial and Answer Modem function blocks.
5.8 Downloadable Serial Communication Protocols
MJ1, MJ2 and MJ3 also support downloadable protocols, such as Allen Bradley DF1, CsCAN Master, GE
Fanuc SNP and Modbus Master.
NOTE: Refer to the download section of the Horner websites for the list of latest supported protocols.
Page 25 of 110