Extron electronic IPL T SF24 Bidirectional serial control interface ports, Digital output

Communication and Control, cont’d

If the integrator selects threshold voltages that are more than 0.1V apart, a deadband, or hysteresis, will be established.

In the example below, the lower threshold voltage is set at +6VDC and the upper threshold is set at +16VDC. The colored bands show state changes on the logical outputs.

The range between 6-16VDC is the deadband in which the signal can fluctuate without affecting the input state.

	Low
VDC	High
26
24
22
20	Upper
18
	Threshold
16
14
12	Hysteresis
10
	Lower
8
	Threshold
6
4
2
	Time

Figure 4-5 — High and low transitions of adjustable threshold with deadband (hysteresis)

Digital output

When a Flex I/O port is configured as a digital output, it is set to offer two output states: “On” and “Off”. When the port is set to an “On” state, (SW1 is closed), the I/O pin is connected to ground (each I/O port is capable of sinking 250mA max.). When the port is set to the “Off” state, (SW1 is open), the output pin is floating.

If the application calls for TTL compatibility, SW2 can be selected to provide a 2K pull-up resistor to +5VDC.

+5V

+30V

390

I/O

24K SW1

GND

Figure 4-6 — Sample of a digital output port driving an LED using an external +5VDC source

Analog input

When a Flex I/O port is configured as an analog input, the port can measure 0 to 25.3VDC with 12bit accuracy. A DC level will be indicated by a count from 0-4096 (6mv/count).

+30V

+12V

I/O 10

10K

24K

GND

Figure 4-7 — Sample of an analog input for a level adjustment, using a 10K pot

Bidirectional serial control interface ports

The IP Tools family of products has several models that incorporate bidirectional serial control ports. The serial ports allow for control of a wide variety of existing Extron and third- party devices. The most common serial control formats are RS- 232, RS-422, and RS-485. Within the IPL T products, there are two different implementations for the serial control ports: the 9-pin D connector and the captive screw connector.

9-pin D Connectors — On some IPL T units, serial control is accessed through a 9-pin D connector. In this configuration, all three control formats are available and fully software configurable. By selecting the RS-232 format, hardware handshaking (RTS, CTS) is also available. The RS-232 connection uses the same industry standard interface pin-out as found on standard PCs. If selecting either RS-422 or RS-485 formats, verify proper wiring as detailed in figure 2-8. These two formats do not have an industry standard pin-out and will vary from device to device.

Captive Screw Connectors — On other IPL T units, several of the serial interface ports are connected on captive screw terminals. When using the ports on the captive screw terminals, only RS-232 control is available, and hardware handshaking is unavailable. Since RS-232 is the most common control interface encountered, this port configuration allows for quick termination.

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