Baud Rate is the data communication rate between the control module and the computer used for configuration and also
the process controller. Choose from three values: 9600, 19200, and 38400.
Parity: Select Odd, Even, or None. All controllers on one EIA-485 party line should have the same parity settings.
4.3.2 Control Mode Selection
The control mode determines the method used to control scanning of the light screen array. Choose from three main
control modes:
• Continuous Scan Mode
• Serial Host Command Mode
• Gate Mode, which has four options
In Continuous Scan mode, the control module begins a new scan as soon as it updates the outputs from the previous scan.
This is the fastest scan control method; it is used in most analog output applications and whenever continuous updating of
the outputs is acceptable.
Host mode allows the control module to communicate with a host computer or control module via RS-232 (all models) or
RS-485 (discrete-output models only) serial protocol. The host directs the control module to scan on demand and receives
the output data from the control module in binary or ASCII form. Baud rates of 9600, 19200, and 38400 are selectable in the
Serial communications menu. See
(p. 35) for more information on Host mode data format.
Gate mode activates an optically isolated external Gate input between terminals 12 (+) and 13 (-) of the control module. The
Gate input has impedance of 7.5 kΩ and accepts a 10 V dc to 30 V dc signal. A dc device such as a photoelectric sensor or
optical encoder typically supplies the Gate input. Gate input signals must be greater than 150 microseconds in duration; the
time between successive Gate inputs must be greater than the minimum scan time for the light screen array (see
(p. 19) for scan time information).
Gate mode has four options:
• Gate ON: the control module will scan as long as the gate is active.
• Gate OFF: the control module will scan whenever the gate is not active.
• Gate ON/OFF: the control module will scan once for each gate transition from ON to OFF.
• Gate OFF/ON: the control module will scan once for each gate transition from OFF to ON.
4.3.3 Scanning Method
The control module may be configured for one of three scanning methods:
• Straight Scan
• Single-Edge Scan
• Double-Edge Scan
Straight scan is the default mode in which all beams are scanned in sequence from the bottom end (cable end) to the top
end of the array. This scanning method requires the longest scan times and provides the smallest object detection size (2.5
mm, 0.1 in diameter).
Single-Edge scan is used to measure the height of a single object. A good application for this scanning method is box
height measurement. For Single-Edge scan, the system always activates the first beam channel (nearest the cable end, or
bottom). If the first beam is blocked, the sensor performs a binary search to hunt for the last beam blocked. Single-Edge
scan works as follows:
1. The receiver scans only the bottom beam until that beam is blocked.
2. When the bottom beam is blocked, the sensor looks to see whether the middle beam is blocked or made
(unblocked).
3. If the middle beam is made (unblocked), the sensor checks the bottom quarter beam; if the middle beam is blocked,
the sensor checks the top quarter beam. This is called a binary search.
4. This routine continues to narrow the field until the edge is found.
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