Configuring a Remote SCXI System
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The flexible SCXI architecture allows it to acquire and condition signals as a front-end signal conditioning system for plug-in data acquisition (DAQ) devices, or as an external data acquisition system that attaches either directly to the computer parallel port or using an RS-232 or RS-485 serial connection. The parallel port and serial options are referred to as remote data acquisition systems.
This document contains step-by-step procedures for configuring a remote data acquisition systems.
Table of Contents
Remote SCXI Using the SCXI-1200 and a Parallel-Port Connection
I. Equipment Needed
- SCXI-1000 chassis
- SCXI-1200 module DAQ device
- SCXI-1302 terminal block
- Parallel-port cable
- 1. Make sure that the SCXI chassis is powered off. Insert the SCXI-1200 module DAQ device into the first slot of the SCXI-1000 chassis. Connect the parallel port cable from the back of the SCXI-1200 to the parallel port (LPT1) on the back of the computer.
2. Power off the computer. While the computer is powered off, power on the SCXI-1000 chassis and then reboot the computer.
3. For Windows NT, skip steps 3-6. For Windows XP/2000/98/95, go to Start»Control Panel»Add/Remove Hardware.
4. Select No when asked, "Do you want Windows to search for your new hardware?
5. Select Data Acquisition Devices and then SCXI-1200 from the list of devices.
6. Launch Measurement & Automation Explorer (MAX) and refresh (F5). Expand Devices and Interfaces. You should see the SCXI-1200 listed under Devices and Interfaces.
7. For Windows XP/2000/98/95, right-click SCXI-1200 and choose Properties. For Windows NT, right-click anywhere in the empty space and select Insert. Choose SCXI-1200.
8. In the next window, click Modify.
9. The window that pops up has a Port option that appears with a pull-down menu. Pull down the menu, select LPT1, click OK, then click Apply.
10. An error message appears that has to do with the base address or IRQ level. Ignore this error and click Yes to continue.
11. Click Modify again, and select Not Assigned in the Port pull-down menu. Click OK, then click Apply.
12. An error message appears saying that the device did not pass the test. Ignore this error and click Yes to continue.
13. Click Modify again, and select LPT1 again in the Port pull-down menu. Click OK, then click Apply.
14. The device should now pass the test. Run Test Resources to confirm that the device passes.
15. Next, right-click Devices and Interfaces and select Create New. Select SCXI-1000 and click Finish.
16. Configure the correct address and click Next. Click No on the option to auto-detect the modules, then click Next. Choose the SCXI-1200 as the communication path and select Next. Then click Finish.
17. Under Devices and Interfaces, an SCXI-1000 chassis should appear with all four slots empty. Insert the modules in the software by right-clicking each empty module, selecting Insert, and then the correct module.
18. For the SCXI-1200, add the correct terminal block, if applicable, and click Next until you get to Finish.
19. For the other signal conditioning modules, select and configure the module which will connect to the SCXI-1200, including selecting the appropriate terminal block. Then click Finish.
20. Right-click the SCXI-1000 chassis and choose Test. The chassis should be verified.
21. Under Devices and Interfaces, right-click SCXI-1200, then choose Test Panel. Change the channel string to ob0!scx!mdy!z (x is the chassis ID, y is the module slot number, and z is the channel number of the signal source). Use this Test Panel to verify that you are able to acquire a signal through this communication path, and that the acquired signal is acceptable.
22. (Optional) Create a virtual channel and repeat the previous step using your virtual channel name instead of the ob0!scx!mdy!z channel string.
Remote SCXI Using the SCXI-1200, SCXI-2400, and a Serial Connection
- SCXI 1000 chassis
- SCXI-1200 module DAQ device
- SCXI-1302 terminal block
- SCXI-2400 module
- Serial cable (RS-232 or RS-485)
- Parallel-port cable
- 7-inch parallel-Port cable adapter
- SCXI-2400 cable adapter
II. Procedure
1. Make sure that the SCXI chassis is powered off. Insert the SCXI-1200 module DAQ device into the first or second slot of the SCXI-1000 chassis. Connect the parallel-port cable from the back of the SCXI-1200 to the parallel port (LPT1) on the back of the computer.
2. Power off the computer. While the computer is off, power on the SCXI-1000 chassis and then reboot the computer.
3. For Windows NT, skip steps 3-6. For Windows XP/2000/98/95, go to Start»Control Panel»Add/Remove Hardware.
4. Select No when asked, "Do you want Windows to search for your new hardware?
5. Select Data Acquisition Devices and then SCXI-1200 from the list of devices.
6. Launch Measurement & Automation Explorer (MAX) and refresh (F5). Expand Devices and Interfaces. You should see the SCXI-1200 listed under Devices and Interfaces.
7. For Windows XP/2000/98/95, right-click SCXI-1200 and choose Properties. For Windows NT, right-click anywhere in the empty space and select Insert. Choose SCXI-1200.
8. Power off the chassis.
9. Insert the SCXI-2400 module into the first or second slot (whichever one the SCXI-1200 is not in). Connect the SCXI-2400 cable adapter to the back of the module and then connect the 7-inch parallel-port cable from the cable adapter to the back of the SCXI-1200 module.
10. Connect the RS-232 serial cable (null-modem cable) from the front of the SCXI-2400 module to the serial port (COM1) of the computer.
Note: For connection with an RS-485 serial cable, the only difference is the physical hardware connection made from the SCXI-2400 adapter to the RS-485 card in the computer.
The RS-485 connector on the SCXI-2000/2400 uses a screw terminal plug to accept wires from your RS-485 cable. Use a twisted-pair cable to increase noise tolerance. Make the network connections as given in the table below. The following link illustrates the SCXI-2000/2400 to RS-485 DB-9 connection: SCXI-2000/2400 to RS-485 DB-9 connection
Computer RS-485 Port | SCXI-2000/2400 |
TX+ | RX+ |
TX- | RX- |
RX+ | TX+ |
RX- | TX- |
Use the termination resistors at both ends of the RS-485 link. For the twisted-pair cable, 120 W resistors are sufficient. Refer to either the SCXI-2000 User Manual or the SCXI-2400 User Manual for information on using the termination resistors.
11. Insert any other signal conditioning modules into slots 3 and 4. Connect the matching terminal blocks to the front of the signal conditioning module with the signal source connected to the terminal block.
12. Power on the chassis and open MAX. Expand Devices and Interfaces. Right-click SCXI-1200 and choose Properties.
13. In the next windows, select Modify, then Remote, and then OK. Then select Apply. This sets the SCXI-1200 to remote mode.
14. Next, right-click Devices and Interfaces and select Create New. Select SCXI-1000 and click Finish.
15. Configure the correct address and click Next. Click No on the option to auto-detect the modules, then click Next. Choose the SCXI-1200 as the communication path and select Next. Then click Finish.
16. Under Devices and Interfaces, an SCXI-1000 chassis should appear with all four slots empty. Insert the modules in the software by right-clicking each empty module, selecting Insert, and then the correct module.
17. For the SCXI-1200, add the correct terminal block, if applicable, and click Next until you get to Finish.
18. For the SCXI-2400, set the appropriate address and baud rate (9600) by setting all switched to the left except 1, 9, 11. This is the default switch configuration on the SCXI-2400 module.
19. For the other signal conditioning modules, select and configure the module which will connect to the SCXI-1200, including selecting the appropriate terminal block. Then click Finish.
20. Right-click the SCXI-1000 chassis and choose Test. The chassis should be verified.
21. Under Devices and Interfaces, right-click SCXI-1200, then choose Test Panel. Change the channel string to ob0!scx!mdy!z (x is the chassis ID, y is the module slot number, and z is the channel number of the signal source). Use this Test Panel to verify that you are able to acquire a signal through this communication path, and that the acquired signal is acceptable.
22. (Optional) Create a virtual channel and repeat the previous step using your virtual channel name instead of the ob0!scx!mdy!z channel string.
Remote SCXI Using the SCXI-1200, SCXI-2000, and a Serial Connection
I. Equipment Needed
- SCXI 2000 chassis
- SCXI-1200 module DAQ device
- SCXI-1302 terminal block
- Serial cable
- Parallel-port cable
- 7-inch Parallel-port cable adapter
- 1. Make sure that the SCXI chassis is powered off. Insert the SCXI-1200 module DAQ Device into the first slot of the SCXI-2000 chassis. Connect the parallel-port cable from the back of the SCXI-1200 to the parallel port (LPT1) on the back of the computer.
2. Power off the computer. While the computer is off, power on the SCXI-2000 chassis and then reboot the computer.
3. For Windows NT, skip steps 3-6. For Windows XP/2000/98/95, go to Start»Control Panel»Add/Remove Hardware.
4. Select No when asked, "Do you want Windows to search for your new hardware?
5. Select Data Acquisition Devices and then SCXI-1200 from the list of devices.
6. Launch Measurement & Automation Explorer (MAX) and refresh (F5). Expand Devices and Interfaces. You should see the SCXI-1200 listed under Devices and Interfaces.
7. For Windows XP/2000/98/95, right-click SCXI-1200 and choose Properties. For Windows NT, right-click anywhere in the empty space and select Insert. Choose SCXI-1200.
8. Power off the chassis.
9. Connect the 7-inch parallel-port cable from the back of the SCXI-1200 module to the back of the SCXI-2000 chassis.
10. Connect the RS-232 serial cable (null-modem cable) from the front of the SCXI-2000 chassis to the serial port (COM1) of the computer.
Note: For connection with an RS-485 serial cable, the only difference is the physical hardware connection made from the SCXI-2000 adapter to the RS-485 card in the computer.
The RS-485 connector on the SCXI-2000/2400 uses a screw terminal plug to accept wires from your RS-485 cable. Use a twisted-pair cable to increase noise tolerance. Make the network connections as given in the table below. The following link illustrates the SCXI-2000/2400 to RS-485 DB-9 connection: SCXI-2000/2400 to RS-485 DB-9 connection
Computer RS-485 Port | SCXI-2000/2400 |
TX+ | RX+ |
TX- | RX- |
RX+ | TX+ |
RX- | TX- |
Use the termination resistors at both ends of the RS-485 link. For the twisted-pair cable, 120 W resistors are sufficient. Refer to either the SCXI-2000 User Manual or the SCXI-2400 User Manual for information on using the termination resistors.
11. Insert any other signal conditioning modules into the remaining slots. Connect the matching terminal blocks to the front of the signal conditioning modules with the signal source connected to the terminal block.
12. Power on the chassis and open MAX. Expand Devices and Interfaces. Right-click SCXI-1200 and choose Properties.
13. In the next windows, select Modify, then Remote, and then OK. Then select Apply. This sets the SCXI-1200 to remote mode.
14. Next, right-click Devices and Interfaces and select Create New. Select SCXI-2000 and click Finish.
15. Set the appropriate address and baud rate (9600) by setting all switched to the right except 1, 9, 11. This is the default switch configuration on the SCXI-2000.
16. Click No on the option to auto-detect the modules, then click Next. Choose the SCXI-1200 as the communication path and select Next. Then click Finish.
17. Under Devices and Interfaces, an SCXI-2000 chassis should appear with all four slots empty. Insert the modules in the software by right-clicking each empty module, selecting Insert, and then the correct module.
19. For the other signal conditioning modules, select and configure the module which will connects to the SCXI-1200, including selecting the appropriate terminal block. Then click Finish.
20 Right-click the SCXI-2000 chassis and choose Test. The chassis should be verified.
21. Under Devices and Interfaces, right-click SCXI-1200, then choose Test Panel. Change the channel string to ob0!scx!mdy!z (x is the chassis ID, y is the module's slot number, and z is the channel number of the signal source). Use this Test Panel to verify that you are able to acquire a signal through this communication path, and that the acquired signal is acceptable.
22. (Optional) Create a virtual channel and repeat the previous step using your virtual channel name instead of the ob0!scx!mdy!z channel string.
Frequently Asked Questions
Q: Does the slot order of the SCXI-1200 and the SCXI-2400 matter?
A: No. The modules must be in the first two slots, but the order does not matter.
Q: When I try to set the SCXI-1200 as the "Connected To:" device for the SCXI Analog Input modules, why does "Connected To:" selection revert back to "None"?
A: The SCXI-1200 automatically controls the SCXI chassis when it is inserted. You cannot run multiple SCXI-1200 modules in parallel in one chassis, so there is no reason that you would ever want to list it as a "Connected To:" device. For this reason, the "Connected To:" option reverts back to "None".
Q: Can I use two SCXI-1200 modules in one chassis driving SCXI modules in parallel mode?
A: No, the driver does not support this and will not in the future. Although it is theoretically possible from a cabling perspective, the Windows parallel-port drivers limit the throughput, which is likely the main motivation for wanting to have a second module connected.
Q: What mode should I set my parallel port to when I connect the SCXI-1200 to the parallel port?
A: You should set it to EPP mode, which assigns and IRQ to the parallel port. The assignment is usually IRQ 7 with maximum throughput and no DMA. No other mode is supported by National Instruments. This setting is usually made in the PC BIOS rather than the Device Manager.
Q: What should I do if the SCXI chassis loses power or gets power-cycled?
A: Stop your program. Simply powering the chassis on will not cause your programs execution to recover. Restart the PC while the SCXI chassis is powered on. After rebooting, go into MAX and test the chassis. After verifying the chassis, close MAX and restart your program. Another option is to power on the chassis and run the Device Reset.vi in LabVIEW. This VI is found in the Data Acquisition» Calibration and Configuration palette. After running the VI, restart MAX and test the chassis.
Q: Can I auto-detect SCXI modules inserted in the SCXI chassis when it is controlled by the SCXI-1200?
A: No, this option does not work well through the parallel port and is not available at all through the serial port.
Q: What should I do if my SCXI-1200 stops returning data during operation?
A: Stop acquisition and reboot the computer, with the chassis powered on. Then try restarting the acquisition.
Q: Is there a catch-all troubleshooting procedure?
No, but you should always try the following:
1. Check cabling.
2. Power-cycle chassis.
3. Power-cycle computer, while the chassis is powered on.
4. While both the chassis and computer are on, open MAX, refresh (F5), and test the SCXI-1200.
Related Links:
SCXI Installation Wizard
KnowledgeBase 0L5HQ0Y5: WDAQCONF does not find modules in remote chassis with SCXI-1200
KnowledgeBase 0MRC7KNI: How fast of an WFM update rate can you use on a remote SCXI-1200?
KnowledgeBase 0MRF1N03: What level of performance should I expect from a remote SCXI system?
KnowledgeBase 0P39OOL7: What are the sustainable continuous acquisition rates using remote scxi?
KnowledgeBase 0U0DSR9B: SCXI Channel Addressing with Multiple Chassis
Knowledgebase 16P92VBS: Problems Adding Multiple SCXI-1200 Modules in a Multiple-Chassis Remote SCXI System under Windows 95/NT
KnowledgeBase 1G89TPKD: Is Remote SCXI Supported on the Macintosh Platform?
KnowledgeBase 1YQGR89V: I Get Error -10401 when Using the SCXI-1125 with Remote SCXI
KnowledgeBase 27P8S5J6: Does the NI-DAQ OPC Server Support Remote SCXI?
KnowledgeBase 2EO93DKZ: Can I Auto-detect Modules in a Remote SCXI System when Connected by RS-232 to the SCXI-2400?
KnowledgeBase 1S1GK9KO: SCXI-1200 Returns a Base I/O Address Error When the Chassis Is Not Powered On before the Computer Is
KnowledgeBase 23TF4PQ1: My SCXI-1200 Won't Pass the "Test Resources" Test Using NI-DAQ 6.8 and MAX 2.0
KnowledgeBase 21DDN2HE: How Does the SCXI-1200 Work?
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