Detcon 6400-N1P - Manual (Page 12)

1600/6400-N1P
1600/6400-N1P- Instruction Manual Rev. 1.1 Page 8 of 38
Figure 10 Model AO-4 Module
Contact Input Modules
There are four addressable contact inputs in each DI-4 Module. The Module is powered by 24VDC, and the
voltage is used to produce a 4mA level when the contacts are open and a 20mA level when the contacts are
closed.
Figure 11 Model DI-4 Module
General Wiring Notes:
When I/O Modules are located at a remote distance from the controller, an end of line terminating resistor
is required to enhance communications reliability. Identify the last I/O Module in the loop, and open the
module casing using the clip release points. Locate and install the jumper on JP6. This adds a 120
Ω
resistor to the end of the line. If applicable, add a 120
Ω resistor to the last Modbus™ gas sensor.
Follow generally accepted guidelines for RS-485 serial networks. Do not wire I/O Modules and/or
Modbus™ gas sensors in long-distance ‘T-Tap’ configurations. Stay with direct serial configurations. See
Section 14.0 Appendix for serial communications configuration guidelines.
Use Detcon Recommended cabling whenever possible.
• Belden P/N 1502P cable is recommended for a single cable providing serial communications and
power.
• Belden 9841 cable is recommended for a single cable providing serial communications only.
Ground the cable shielding at the Model 1600/6400-N1P Controller only. Other points of grounding may
cause a ground loop, and induce unwanted noise on the RS-485 line, which in turn may disrupt
communications.