Analog c-pod

Introduction

Analog c-pod is different from other c-pod models: The other models typically have 8 or 16 physical output lines; a signal is indicated when the voltage on one of these lines alternates between 0 and 5 volts.

Analog c-pod has a single physical output line. The voltage level that it produces is determined by three options:

Voltage Range. The factory default is for Analog c-pod to produce output between 0 and 1 volt. The maximum is 0 to 10 volts. You can change the output range in increments of 1 volt.
Voltage Levels. When in Fixed Delta analog mode (see below), Analog c-pod can divide the voltage range into 8 or 16 levels. The idea is to overcome the limitation of having a single physical line so you can have richer information. When in Binary mode (also see below), the voltage range can have up to 255 different levels.
Analog Mode. This determines how Analog c-pod creates the voltage levels.

Analog Modes

Analog c-pod offers two modes: Fixed Delta and Binary.

Fixed Delta mode is simpler: c-pod divides the voltage range by the number of levels. For example, with 8 levels and a 0 to 10 volts range, the output is:

Bit 0: 1.25V (that’s 10 volts divided by 8)
Bit 1: 2.5V (the value of Bit 0 multiplied by 2)
Bit 2: 3.75V
Bit 3: 5V
Bit 4: 6.25V
Bit 5: 7.5V
Bit 6: 8.75V
Bit 7: 10V (the value of Bit 0 multiplied by 8)

The main advantage of Fixed Delta mode is that it makes data analysis easier. You have only 8 (or 16) evenly distributed voltage levels to interpret. The disadvantage is that bits cannot be combined: the output will always be that of the most significant bit; any lower bits are ignored. For example, if you send a command to Analog c-pod to activate bits 6 and 7 at the same time, the output will be 10V (bit 7). The default is 16 levels.

Binary mode is more powerful but might make analyzing the data more difficult. With a 0 to 10 volts range, the output is:

Bit 0: 0.04V (the value of Bit 1 divided by 2)
Bit 1: 0.08V (the value of Bit 2 divided by 2)
Bit 2: 0.16V
Bit 3: 0.31V
Bit 4: 0.63V
Bit 5: 1.25V
Bit 6: 2.5V (the value of Bit 7 divided by 2)
Bit 7: 5V

The advantage of binary mode is that bits can be combined. You can have up to 256 different voltage levels. For example, if you send a command to Analog c-pod to activate bits 6 and 7 at the same time, the output will be 7.5V (2.5V + 5V).