141
Rev. 1.1
2018/04
400-820-9661
M2DC Series Hardware Manual
Pin definitions are as follows:
PIN
Definition
4, 5, 7, 8
GND
1
RX+
2
RX-
3
TX+
6
TX-
9.2.2 RS-485 Connection Method
RS-422/485 communication allows connection of more than one drive to a single host PC, PLC, HMI
or other computer. It also allows the communication cable to be long. The use of Category 5 cable is
recommended as it is widely used for computer networks, is inexpensive, easily obtained and certified for
quality and data integrity.
The M2 drives can be used with either Two-Wire or Four-Wire RS-422/485 implementation. The
connection can be point-to-point (i.e. one drive and one host) or a multi-drop network (one host and up to
32 drives).
Four-Wire Configuration
Four-wire systems utilize separate transmit and receive wires. One pair of wires must connect the host’s
transmit signals to each drive’s RX+ and RX- terminals. The other pair connects the drive’s TX+ and TX-
terminals to the host’s receive signals. A logic ground terminal is provided on each drive and can be used
to keep all drives at the same ground potential. This terminal connects internally to the DC power supply
return (V-), so if all the drives on the RS-422/485 network are powered from the same supply it is not
necessary to connect the logic grounds. One drive’s GND terminal should still be connected to the host
computer ground.
Two-Wire Configuration
In a 2-wire system, the host must disable its transmitter before it can receive data. This must be done
quickly before a drive begins to answer a query. The M2 drives include a transmit delay parameter that
can be adjusted to compensate for a host that is slow to disable its transmitter. This adjustment can be
made over the network using the TD command, or it can be set using the M Servo Suite software. It is not
necessary to set the transmit delay in a four wire system.
NOTE: For RJ45 crystal connector, we recommend standard CAT5 cables.
