B&B Electronics RS-485 manual Inputs #0-10, Ref Input +

Chapter 2 - Connections

This chapter will cover the connections required for the 485SDA10. There are four sets of connections:

∙A/D converter

∙Digital I/O

∙Serial port

∙Power supply

Do not make any connections to the 485SDA10 until you have read this chapter.

CAUTION: When making electrical connections it is important to power down the devices being connected. If this is not possible, precautions must be taken to ensure electrical specifications are not exceeded.

NOTE: If you do not intend to use a section (A/D or I/O), it is still important to read each one.

A/D Connections

The A/D connections are made on the I/O port, which is a DB- 25S (female) connector. Table 2.1 shows the pinout of the I/O port. The next sections explain the functions and connections for the various analog signals.

A/D Inputs #0-10

These are the analog input channels. The analog data that is read from the 485SDA10 is related to the voltage on these pins. Connect your devices to the analog input channels. Voltages on these inputs must remain between 0 and 5.0V DC. Connect unused A/D inputs to analog ground.

A/D Ref Input +

The voltage connected to this pin determines the upper end of the input voltage range. For proper operation, this pin must be connected to a DC voltage between +2.5 and +5.0 Volts. The 485SDA10 provides a 5.0V +/-0.5% reference on pin 17. The 5V reference can be used if you require a 0 to 5V DC input range. If your application requires a better reference voltage or a different input range, you must supply the appropriate reference to the A/D Ref Input+ pin. This voltage must be at least 2.5V greater than A/D Ref Input-.Bypassing the A/D Ref Input+ pin with 0.01μF ceramic and 10μF tantalum capacitors to analog ground will decrease noise levels.

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