www.instrument.com - Friday, August 29, 2008
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Frequently Asked Questions

EDAS-1002E /1031E Multifunction

EDAS-1001E Digital

1. How many users can communicate with an EDAS unit at the same time?
2. Does the EDAS unit have on-board memory for storing data locally?
3. Can the EDAS run programs locally?
4. What is the maximum data transfer rate of analog input on an EDAS unit?
5. When performing continuous data acquisition, how are samples stored on the unit?
6. Does the EDAS support dynamic IP addressing using DHCP?
7. Does the EDAS support SNMP?

1. How many users can can communicate with an EDAS unit at the same time?

Up to 8 clients can talk to a single EDAS unit, but the ports these clients read or write data to or from must be configured the same way. That is, a port cannot be an input and an output at the same time. (Provisions to lock-out other users from attempting to alter the EDAS unit’s configuration are provided through software support.)

2. Does the EDAS unit have on-board memory for storing data locally?

No. The EDAS has a circular buffer which is used to temporarily store data until it is packetized (using TCP/IP) and sent to a host PC over Ethernet. The size of the circular buffer is configured through software when setting up high-speed analog input. The maximum size of the buffer is 32,767 KB.

3. Can the EDAS run programs locally?

No. The EDAS must be configured and controlled by application software running on a host computer.

4. What is the maximum data transfer rate of analog input on an EDAS unit?

EDAS throughput is variable and will depend on several factors, particularly the mode of acquisition you've specified. The multifunction EDAS can be used in two high-speed analog input modes: frame (scope) and continuous (streaming) mode.

When used in frame mode, the EDAS records a snapshot of the signal being sampled. This mode is ideal for transient capture applications, as well as signal analysis and oscilloscope types of applications. Sampling rate can be set to the unit's maximum possible rate. The analog-to-digital converter (A/D) on the multifunction EDAS models (EDAS-1002E) samples at 100kHz. Sample size can be set to approximately 10,000 samples. The unit may not be able to store sample sizes higher than 10,000 samples at the maximum sampling rate due to memory restrictions on the unit. Once the snapshot of your signal is stored by the EDAS, it is packetized (using TCP/IP) and sent to the PC running your application software.

When used in continuous (streaming) mode, the maximum sampling rate of the current version of the EDAS-1002E unit is around 3000 Hz. Faster sampling rates will cause the unit's onboard circular buffer to fill up with data and over-run conditions will occur. Increasing the size of this buffer (Maximum Samples) may help to extend the amount of time a software application can run without incurring over-run conditions; however over-run will eventually occur if you set the Sample Rate above 3000Hz.

5. When performing continuous data acquisition, how are samples stored on the unit?

Samples are stored onboard the EDAS until there is such a delay that the samples are overwritten by new incoming samples. Here is how it works:

For streaming applications, a circular buffer is used to provide gap-free, continuous data acquisition. Incoming samples are stored in the circular buffer until they are moved to an Output buffer to be packetized for transmission over Ethernet. During each execution cycle, data is transferred from the circular buffer to the output buffer.

The sizes of the circular buffer (Maximum Samples) and output buffer (Total Samples) can be set by the user through software. The maximum size of the circular buffer is 32,767K. The size of the output buffer determines the amount of data to be packetized in a single execution cycle; it should be less than or equal to the size of the circular buffer.

The High-Speed Analog Input DLL generates a Boolean "Overrun" output when data in the circular buffer was overwritten before it was transferred to the Output buffer. The optimal values for the circular buffer size and output buffer size should be determined empirically using this Overrun output. For very High-Speed streaming applications, we recommend at least an 8:1 ratio of circular buffer size to output buffer size.

6. Does the EDAS support dynamic IP addressing using DHCP?

EDAS 1000 Series models do not support use of the Dynamic Host Configuration Protocol. IP addressing must be configured through the EDAS unit's RS-232 COM port using configuration software (SYSCHECK) provided with the unit. See EDAS CE EDAS 2000 Series ..

7. Does the EDAS 1000 Series support SNMP?

EDAS 1000 Series models do not support the Simple Network Management Protocol. See EDAS CE EDAS 2000 Series ..