Measurement Computing USB-1608FS - Manual (Page 12)

USB-1608FS User's Guide
12
Channel-Gain queue
The channel-gain queue feature allows you to configure a different gain setting for each analog input channel.
The gain settings are stored in a channel-gain queue list that is written to local memory on the device.
The channel-gain queue list must contain all eight channels listed in consecutive order. An example of the
channel-gain queue list is shown in the table below.
Sample channel-gain queue list
Element Channel Range
0 CH0 BIP10V
1 CH1 BIP5V
2 CH2 BIP10V
3 CH3 BIP1V
4 CH4 BIP2V
5 CH5 BIP10V
6 CH6 BIP1V
7 CH7 BIP5V
Carefully match the gain to the expected voltage range on the associated channel or an over range condition
may occur. Although this condition does not damage the device, it does produce a useless full-scale reading,
and can introduce a long recovery time due to saturation of the input channel.
Digital I/O
You can connect up to eight digital I/O lines to DIO0 through DIO7 . Each digital channel is individually
configurable for input or output. During initial power on or reset the digital pins are set for input.
The digital I/O terminals can detect the state of any TTL-level input. Refer to the schematic shown in Figure 4.
Figure 4. Schematic showing switch detection by digital channel DIO0
If you set the switch to the +5 V input, DIO0 reads TRUE (1). When set to GND, DIO0 reads FALSE (0).
Pull-up/down configuration
Boards designed with hardware revision E and later have a user-configurable internal jumper to configure the
digital bits for pull-up (default) or pull-down. The hardware revision is listed with the part number on the
bottom of the device, for example P/N 193334E.
If the p/n of your board is earlier than hardware revision E, the default configuration is pull-up. To configure for
pull-down, the board must be modified at the factory.
If your board has a user-configurable jumper, complete the following steps to set the pull-up/down
configuration:
1.
Unplug the device from the computer.
2.
Turn the device over and rest the top of the housing on a flat, stable surface.
Caution! The discharge of static electricity can damage some electronic components. Before removing the
USB-1608FS from its housing, ground yourself using a wrist strap or touch the computer chassis
or other grounded object to eliminate any stored static charge.
3.
Remove the three screws from the bottom of the device using a #1 Philips head screwdriver.
4.
Hold both the top and bottom sections together, turn the device over and rest it on the surface, then
carefully remove the top section of the case to expose the circuit board.