There are two parts to configuring an analog transducer:
Select the mode of operation of each analog channel
Select the analog transducer type (input Voltage or current range)
Each is described in this topic.
Select the Analog Channels Modes of Operation
The Analog Board Configuration dialog is used to select the mode of operation for each analog channel. To display this dialog:
On the Tools menu, click Module Configuration.
In the Slots list, click an analog module.
Click Slot options.
Many channel assignment options will be offered. Depending on the hardware and firmware present, some of the options may be disabled. See the descriptions below for a description of each operational mode and its possible uses.
To change the analog channel usage:
Click the Channels 0-1 tab.
Click the option button for your desired use for these channels.
Click the Channels 2-3 tab.
Click the option button for your desired use for these channels.
Click Update RMC.
The Update Module Configuration dialog box will be displayed to indicate the progress. If the RMC could not be reset automatically, you may be prompted to reset the RMC manually.
In the RMC Configuration dialog box, click Close.
Each channel-assignment option button gives the assignment of both channels. Some options assign the channel to a joint purpose, as in the case of differential force, some assign the channels to different purposes, and some assign the channels to the same purpose. Following are descriptions for each individual channel assignment:
Position Control
This mode uses a single analog channel and an analog drive output. Standard closed-loop position control may be performed on this axis.
Position Reference
This mode uses a single analog channel. This channel does not have an output and therefore cannot be used as in closed-loop control, but instead may provide a reference for another controlling axis. A common use for this type of axis is to serve as the master to another axis from a signal generated from a PLC or joystick.
Velocity Control
This mode uses a single analog channel and an analog drive output. The input channel value is assumed to indicate velocity, as given by a device such as a tachometer or velocity-control joystick. The drive output will work in conjunction with the input channel to control the speed of the axis.
Velocity Reference
This mode uses a single analog channel. The input channel value is assumed to indicate velocity, as given by a device such as a tachometer or velocity-control joystick. This channel does not have an output and therefore cannot be used as in closed-loop control, but instead may provide a reference for another controlling axis. A common use for this type of axis is to serve as the master to another axis from a speed signal generated from a PLC or velocity-control joystick.
Pressure Control
This mode uses a single analog channel and an analog drive output. The input channel is connected to a pressure transducer, the drive output is connected to the pressure-controlling valve or motor, and they work together to hold a pressure or ramp the pressure in closed-loop control.
Pressure Reference
This mode uses a single analog channel. The input channel is connected to a pressure transducer, but because it has no drive output, it cannot close the loop. Therefore, this input can only be used as a reference for another pressure control input. That is, a pressure control input/output pair can use a pressure reference input as its target pressure.
Auxiliary Pressure
This mode uses a single analog channel. This mode acts the same as Pressure Control mode described above, except that there is no drive output, so another axis’ drive output must be used. The most common reason for doing so is to have a system with a position-to-pressure transition. In this case, a position control axis is assigned to the auxiliary pressure channel. The position transducer is connected to the position control axis’ input, the pressure transducer is connected to the pressure channel, and each of the position and pressure inputs use the drive output when it is in control.
Differential Force Control
This mode uses both channels in the pair and an analog drive output. The input channels are connected to pressure transducers, the drive output is connected to the force-controlling valve or motor, and they work together to hold a force or ramp the force in closed-loop control.
The first channel’s input will be converted to a force using the Scale A and Offset A parameters, and will be displayed in the Actual Force A field. The second channel in the pair (channel 1 or 3 depending on the pair) will be converted to a force using Scale B and Offset B, and will be displayed in the Actual Force B field. Then, Force B will be subtracted from Force A to give the Actual Force, which is used for differential force control.
Auxiliary Differential Force
This mode uses both channels in the pair. This mode acts the same as Differential Force Control mode—described above—except that there is no drive output, so instead another axis’ drive output must be used. The most common reason for doing so is to have a system with a position-to-force transition. In this case, a position control axis is assigned to the auxiliary differential force channel. The position transducer is connected to the position control axis’ input, the pressure transducers are connected to the differential force channels, and each of the position and force inputs use the drive output when it is in control.
Auxiliary Analog
This mode uses a single analog channel. This mode is no longer supported.
Auxiliary Differential Analog
This mode uses both channels in the pair. This mode is no longer supported.
Note: At no time will the RMC100 allow more than eight axes. Any extra axes will be ignored. For example, suppose a system has one 2-axis MDT card and two 4-channel analog cards. If all eight channels are configured as single-ended analog axes, then this would total ten axes, which is not allowed. Therefore, the last two channels on the last analog card will not be usable.
Select the Analog Transducer Type
Use bits 12-15 of the Configuration word to select one of the following input ranges as described in that parameter’s topic:
Voltage: 0 to 10V
Voltage: -10V to +10V
Voltage: 0 to 5V
Voltage: -5V to +5V
Current: 4 to 20mA
See the COUNTS topic for detailed information on the maximum and minimum limits of the various analog input ranges.
See also:
Using Analog Channels as Position Inputs
Using Analog Channels as Velocity Inputs
Using Analog Channels as Pressure Inputs
Using Analog Channels as Differential Force Inputs
Copyright (c) 1997-2015 by Delta Computer Systems, Inc.