CTI Products IOB I/O Interface - Manual (Page 9)

IOB Hardware Reference Theory of Operation
CTI Products, Inc.
68-11168-105
4
3. Theory of Operation
This section describes the operation of the IOB module in an I/O control system.
This module can operate in one of four different modes:
I/O Group Mode 1 Mode 2 Mode 3 Mode 4
1
2
1 of 4 Select 1 of 4 Select
3 # 1
4 Independent 1 of 8 Select
5 I/O
6 1 of 4 Select Independent
7 # 2 I/O
8
The operating mode is set using the OPTION switches on the module’s front
panel. Refer to section 4 for a description of the mode setting switches and
section 5 for a pinout of the IOB’s I/O connector. The functions of the I/O
connector pins on the rear of the module change depending on the IOB’s
operating mode.
Each operating mode is discussed in the following sections.
3.1 Controlling the I/O
The MCN HIB module, along with the MCNRCD Remote Comparator Display
program, provides a PC based user interface for the IOB module. Output points
on the IOB can be controlled by either the PC keyboard or mouse. Input points
can be monitored on the screen.
In order to have the MCNRCD software display meaningful I/O status messages,
custom status text categories and custom status messages must be created for your
specific I/O application (see the appendix titled Changing Status Message Text in
the Monitoring and Control Network Remote Comparator Display Software
Manual (reference 2) for details about creating custom status messages). These
custom status messages are defined in the file MCNRCD.CFG.
Section 7 provides a number of examples that show how to customize the
MCNRCD display for an IOB module.
3.1.1 Input Monitoring - I/O Groups and I/O Bits
With the MCNRCD software, a single display position on the screen does not
represent a single I/O point. Instead, each display position represents the state of
four I/O points. We refer to the four I/O points that make up a screen display
position as an I/O group (this is similar to the 4 bits, Vote Rx, Disable, and Fail
associated with a receiver in comparator applications using a CIB module).