Honeywell CP-600E, Manual

WEB-600E AND CP-600E NETWORK CONTROLLERS

11

62-0433—01

The controller is a serial DTE device, such that another DTE 

device (PC, for example) requires a “null modem” cable. If 

connecting to a DCE device such as a modem, use a straight-

through cable. Table 2 provides standard serial DB-9 pinouts.

NOTE: If rebooted with the mode jumper in the “Serial 

Shell” position (see Fig. 3), the RS-232 port pro-

vides “system shell” access. See the 

JACE Niag-

araAX Install and Startup Guide

 for related 

details.

.

RS-485

An RS-485 port uses a 3-position, screw terminal connector, 

and always operates as COM2. As shown in Table 2 pinouts, 

from left-to-right the screw terminals are shield (S), plus (+), 

and minus (–). Wire in a continuous multidrop fashion to other 

RS-485 devices, meaning “minus to minus,” “plus to plus,” and 

“shield to shield.” Connect the shield to earth ground at one 

end only, such as at the controller.

RS-485 Biasing

The RS-485 port on the controller’s base board has a pair of 

two-pin jumpers that can be shorted with jumper blocks to 

provide “biasing.” As shipped from the factory, these pins are 

not shorted, thus the RS-485 port is unbiased.

NOTE: See Need for RS-485 Bias before following the 

Adding RS-485 Bias procedure. In many cases, 

the default unbiased RS-485 port is preferred.

Need for RS-485 Bias

NOTE: A full discussion of communication line termina-

tion is beyond the scope of this document.

Biasing sometimes improves RS-485 communications by 

eliminating “indeterminate” idle states. When you install two, 

2-pin shorting blocks on the controller’s RS-485 bias jumper 

pins, this adds two onboard 3.3K ohm resistors into the 

controller’s RS-485 circuit, as follows:

• from RS-485 “+” to 5V.

• from RS-485 “-” to Ground.

NOTES: In general, 

only one device

 on an RS-485 trunk should 

be biased. Otherwise, undue loading of the circuit 

may result, with fewer devices supported.

RS-485 bias resistors are 

different

 than “termination 

resistors,” externally installed at the two physical 

ends of a daisy-chained RS-485 trunk, across the “+” 

and “–” terminals. Termination resistors are typically 

100 or 120 ohm value resistors.

Whenever termination resistors are used, RS-485 

biasing is typically required.

Adding RS-485 Bias

To add biasing, you must power off the controller and remove 

some assemblies (including metal shield and the NPM6E 

processor module) to access the base board jumper pins, 

located behind the RS-485 port. Then you must reposition the 

two shorting blocks on these jumper pins. Then you 

reassemble the unit by remounting the NPM6E processor 

module, hex standoffs, metal shield, and shield screws.

WARNING

Remove all power from the controller before 

working on the unit. Observe static discharge 

precautions. See “Static Discharge Precautions” 

on page 2.

If the controller is already installed or mounted, it is 

recommended that you remove it first. Then work on a flat, 

stable, well-lit work surface.

Table 3. Base Serial Port (RS-232 and RS-485) Pinouts.

Base RS-232 DB-9 Port (COM1)

 RS-485 Port 

(COM2)

Pinout Reference

Signal

DB-9 
Pin

Pinouts

DB-9 Plug (male)

DCD

Data carrier detect

1

3-Position connector 

(male)

RXD

Receive data

2

TXD

Transmit data

3

DTR

Data terminal ready

4

GND

Ground

5

DSR

Data set ready

6

RTS

Request to send

7

CTS

Clear to send

8

not used on the JACE

9

S

–

+