Serial Communications - Honeywell CM4 Technical Handbook

CM4 Four-Point Continuous Monitor
10.1 Communications Options
There are two optional communications features available for the
CM4 monitor:
•

Serial communications

• Printers
10.1.1 Serial Communications
The rear panels of the CM4 monitor allows installation of up to two
optional serial interface ports. These ports are designed to allow output
to printers and other devices, and two-way communication between
the CM4 monitor and another device.
There are five serial interfaces available for the CM4 monitor, each
designed for a specific communication application. The options are:
• RS-232 for serial printer or remote unidirectional ASCII
interface (15 ft. max. distance)
• RS-232 for remote bidirectional binary communication
• RS-422 for serial printer or remote unidirectional ASCII interface
• RS-422 for remote bidirectional binary communication
• RS-485 for remote multi-drop bidirectional binary communication
via two-wire transmission
• L W - a bus system that per mits peer-to -peer
o n o r k s
communication information
The printer port is always unidirectional. The communications port is
always bidirectional.
The serial communications ports are connected to the remote device(s)
with 9-pin (DB9) plugs and cables.
information on selecting the communications ports.
For more detailed information on serial communications, request
Technical Note T/N 1998-0082 or
Protocol.
CM4 Technical Manual
Sections 7.4.1 and 7.4.2
Appendix E, Serial Communications
10.1.2 Printers
Up to nine CM4 monitors can send data to a single serial printer in
a summary format. There are two printer options available, one for
desktop and one for rack-mount applications. For complete instructions
on the printer options, refer to
10.2 Remote Alarm Reset Option
The remote alarm reset option provides the ability to reset the CM4
alarm conditions for any individual point from a remote location. There
are two ways to connect the remote reset circuit:
• using an external 24V DC power supply
• using the CM4 unit's internal 24V DC system
The remote alarm reset option is factory-programmed with the
purchase of the CM4 monitor. The factory-programmed setting must be
performed by an authorized Honeywell field service engineer. External
wiring, power supply, and switches are user-supplied items.
The following information will describe the two types of alarm reset
circuits, wiring, and recommendations for installing an alarm reset
system.
10.2.1 How it Works
The remote alarm reset option works similar to the reset button on the
CM4 instrument. However, the remote option will allow resetting an
alarm from individual points, while the reset button on the CM4 unit
resets all alarms from all points at once. An additional advantage to
the remote reset option is it can be located away from the CM4 unit. In
provide
an alarm condition, momentarily pressing (0.250 seconds minimum)
the remote reset button will reset the individual point's alarm. This will
also reset all fault indications on the instrument.
10-2
Appendix D, Printer Options.