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AM16/32B Relay Analog Multiplexer

multiple sensor types are connected to the AM16/32B, Mode B allows one

sensor type to be measured more frequently than the other sensor types. A

more detailed description of Mode B is provided in section 4.2.1.2.

The AM16/32B detects a certain sequence on the RESET and CLK inputs to

determine if it should operate in Mode A or Mode B; it does this every time the

RESET line goes from LO to HI.

4.1.2.1 Mode A

The AM16/32B operates in Mode A under the following circumstances:

• RESET HI for more than 9 ms.

• A CLK pulse occurs while RESET is HI.

When reset first goes high, the common terminals (ODD H, ODD L and

EVEN H, EVEN L) are disconnected from all sensor input terminals. When

the first clock pulse arrives, the “COM” terminals are switched to connect with

sensor input channel 1 (blue lettering) consisting of 1H, 1L, 2H, and 2L.

When a second clock pulse arrives, the common lines are switched to connect

to channel 2 (3H, 3L, 4H, 4L). The multiplexer advances on the leading edge

of the positive going clock pulse.

The CLK pulse should be at least 1 ms long. A delay (typically

10 to 20 ms) is inserted between the beginning of the CLK pulse

and the measurement instruction to ensure sufficient settling time

to relay contacts.

NOTE

4.1.2.2 Mode B

To go into Mode B, the RES line must be set HI for 5 ms (±1 ms) without any

clocking. Then, the RES line needs to be set LO. After the RESET has been

set low, the AM16/32B counts the number of CLK pulses that occur before the

RES line is activated again. This number is the relay address. After getting

into Mode B, the rising edge of RESET (<75 msec after last CLK pulse)

activates the addressed relay. Once the addressed relay is activated, the

AM16/32B advances to the next relay with each CLK pulse (see Figure 4).

If the time between the falling edge of the 5 ms RESET pulse

and the next rising edge of RESET or CLK is longer than 125

ms, the AM16/32B will go into Mode A.

NOTE

Section 4.1.2.3 includes a portion of a CR1000 program that shows the

instructions used to go into Mode B and jump to channel 6.

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Campbell AVW1 Spezifikationen Seite 13