User`s manual

Western Reserve Controls, Inc. 1782-JDO User’s Manual
PRELIMINARY
16
4.3 Serial Port Connector
The ASCII devices are connected to the JDO via a 3-wire communications cable. See your
ASCII device’s User Manual for details on the proper connections.
The RX and TX designators are referenced with respect to the JDO.
Table 4-3 RS-232 / RS-485 Connector Signals
Pin # Designator RS232 Signal RS485 Signal
3 RX Receive Signal -
2 TX Transmit Signal +
1 GND Ground Common
4.4 DeviceNet Configuration
DeviceNet specifications provide for a maximum network distances for the main trunk line
and drop lines, depending upon the baud rate used on the network. See Table 4-4
Table 4-4 Maximum Network Cable Lengths
Trunk Line Length Drop Length
Maximum Distance Maximum Cumulative
Baud Rate Meters Feet Meters Feet Meters Feet
125k baud 500 m 1640 ft 6 m 20 ft 156 m 512 ft.
250k baud 250 m 820 ft 6 m 20 ft 78 m 256 ft.
500k baud 100 m 328 ft 6 m 20 ft 39 m 128 ft.
4.4.1 DeviceNet Network Termination
A DeviceNet system must be terminated at each end of the trunk line. The host controller
and the last JDO or other DeviceNet device on the network must always be terminated to
eliminate reflections, even if only two nodes are present. The DeviceNet specifications for the
terminating resistor are:
• 121 ohm
• 1% metal film
• 1/4 Watt
An appropriate terminating resistor, WRC part number RM121DN, may be purchased from
WRC.
IMPORTANT: Per the DeviceNet spec -- do not terminate devices on drop lines.
4.4.2 DeviceNet Connection Wiring
The JDO uses a 5-pin plug-style DeviceNet connector, which has male pins.