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About BASIC I/O
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BASIC I/O Hardware User ManualChapter 1BIO4, BIO8 and BIO16 (not AD) Products |
BASIC I/Os are a family of small, industrial grade, remote data acquisition and control systems which exchange data with a Host computer via a serial communication link. Controlled by a wide range of software running in a Host computer, BASIC I/Os are located near the sensors and actuators. The serial link eliminates the need for expensive and noise prone signal wiring between field sensors and actuators, and a central control room.
Each BASIC I/O system consists of one logic board connected to a 4, 8, or 16 position I/O module mounting rack. This combination is then field configurable to accept either analog or digital electrically isolated input or output modules which can interface to a wide variety of sensors and actuators.
BASIC I/O networks can serve over 4000 analog and/or digital I/O lines in various combinations.
User selected serial communications between the Host and the first BASIC I/O can be RS-422 or RS-485. These communication links allow the units to operate up to 5000 feet apart. Baud rates from 300 to 38,400 are available.
The BASIC I/O instruction set core complies 100% with that of the OPTO-22 Optomux. With this ASCII character, speak-only-when-spoken-to protocol, a Host transmits inquiry requests to the BASIC I/O to determine the status of its various process inputs. Similarly, the software in the Host computer makes control decisions and transmits instructions to the BASIC I/O, which in turn, makes the proper changes to its various outputs. Both the Host and it's communication link are essential elements in this data acquisition and process control scheme.
Software for use with the BASIC I/O system can be obtained from a variety of sources. Nearly every third party SCADA software vender has developed a driver which is compatible with this system. In addition, the communication protocol employed by the BASIC I/O product is a published ASCII printable standard. This makes developing your own software a simple matter.
duTec also offers a software solution called EASY I/O. With this package, custom QuickBASIC source code is generated to fit the signals located on the BASIC I/O. Once configured, a simple data acquisition program is automatically generated. This sample can then be altered to fit the particular needs of the user.
A notable feature of the BASIC I/O is it's ability to gather data and perform ranging and statistical operations on raw data before it is sent to the Host. Thus the Host can spend less time manipulating data and more time gathering it. The following sections discuss the different signals the BASIC I/O can handle.
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duTec analog input modules are 100% isolated and accept a wide range of voltages, currents, the outputs of thermocouples, RTDs, and 590 type temperature probes.
BASIC I/O instructions provide linearized thermocouple and RTD sensor data. Engineering unit conversion is performed by the Host software, such as duTec's EASYI/O program generator.
The BASIC I/O samples individual analog inputs at the constant rate of 100 samples per second. The effective sample rate per channel is determined by the total number of channels to be sampled.
| Input Value | Determines signal levels, with 12 bit (1 part in 4096) resolution. |
| Offsets | Input values can be software offset, or "zeroed", with 12 bit (1 part in 4096) resolution, over the module's specified range. |
| Gain/Slope | The amplitude of input values can be software multiplied by factors ranging from 0.25 to 4.0. |
| Range Limits | The occurrence of input values falling out of user defined upper or lower limits can be flagged. |
| Minimums | The minimum level of input values can be captured. |
| Maximum | The maximum level of input values can be captured. |
| Averages | Can calculate average input amplitude for 1-65,535 samples. |
| Temperature | Provides linear temperature in C for thermocouples, RTD and type 590 temperature probes. |
Thermocouple modules provide cold reference junction compensation.
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Analog output modules are 100% isolated. These self-sourcing modules provide the voltage or current necessary to drive standard instrumentation loads. All outputs are updated every 10 milliseconds or 100 times per second.
| Level Value | Can set output levels, as a fraction of the module's full scale range, and are specified with 12 bit (1 part in 4096) resolution. |
| Waveforms | Can provide square, triangular, sawtooth or ramp waveforms. Maximum and minimum amplitudes, as a fraction of the output module's full scale range, are specified with 12 bit (1 part in 4096) resolution.Waveform periods are specified from 0.1 to 6,553 Seconds (about 109 minutes). |
Digital input modules detect the absence or presences of a field signal. Module types vary from AC to dry contact sense. Because these industry standard modules are optically isolated, the response time performance of digital input instructions can be limited by the delay in the input modules themselves. Some modules can have a rise and fall time of up to 40 milliseconds.
Digital input instruction types are:
| Read | Read the ON/OFF state of inputs. This data is updated every 10 milliseconds. |
| Edge Detection | OFF-to-ON and ON-to-OFF transitions can be detected within 1 millisecond of their occurrence. Action is only reported every 10 milliseconds. |
| Pulse Widths | BASIC I/Os can report pulse width measurements from .01 seconds to 46.6 hours. Minimum resolution is .01 seconds (pulse widths up to 10.9 minutes). Either on or off pulses can be measured. |
| Pulse Counting | Pulses can be counted up to a total of 65,535. To be reliably counted, pulses must have minimum and minimum ON and OFF times of 1 millisecond. Thus the maximum counting rate for a 50% duty cycle squarewave is once every 2 milliseconds (500 Hz). |
| Frequency | Direct frequency measurements can be made on digital inputs at rates of up to 500 Hz with a user specified time base of from .01 to 2.55 seconds. |
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Digital output modules, commonly referred to as solid state relays, control external AC or DC power sources. A dry-contact (mechanical relay) with very low contact resistance is also available.
Digital output instruction types are:
| Set Outputs | Can set individual multiple outputs ON or OFF |
| Pulse Generator | Can generate 1 to 65,535, 50% duty cycle pulses whose equal ON and OFF periods can range from 0.01 to 2.55 seconds. Resolution can be reduced by a factor of 1-256 on a system wide basis to increase the maximum pulse width available. |
| Modifiers: | |
| One Shot | Can generate ON or OFF pulse durations of up to 10.9 minutes with a resolution of 0.01 seconds. Resolution can be reduced by a factor of 1-256 on a system wide basis increasing duration up to 46 hours. Re-triggering is available. |
| Delayed | Can generate delayed ON or OFF outputs after delaying up to 10.9 minutes with a resolution of 0.01 seconds. Resolution can be reduced by a factor of 1-256 on a system wide basis increasing the delay before changing state up to 46.6 hours. Re-triggering is available. |
| Squarewave | Can generate squarewaves with programmable ON and OFF periods. On and OFF periods have a base range from 0.01 seconds to 10.9 minutes. Resolution can be reduced by a factor of 1-256 on a system wide basis increasing duration to 46.6 hours. |
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Input data throughput is the time from the beginning of the first character of an instruction to the end of the last character of the response. The processing time of the Host computer will reduce the effective throughput.
Output Execution throughput is the time from the beginning of the first character of an instruction to the time when the actual output changes. Because the instruction acknowledgement occurs before outputs actually change state, the processing time of the Host computer controlling output instructions reduce the effective throughput. It is even possible at 38400 baud to instruct the BASIC I/O to turn a digital output on and then immediately instruct it to turn back off so quickly that the module never actually gets activated.
The tables below show milliseconds per channel and channels per second for 1 and 16 I/O channel cases.
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Input (Digital M) |
Output (Digital J) |
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|---|---|---|---|---|---|---|---|---|
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1 Channel |
16 Channels |
1 Channel |
16 Channels |
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Baud |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
300 |
501 |
2 |
501 |
32 |
379 |
3 |
379 |
42 |
600 |
251 |
4 |
251 |
64 |
195 |
5 |
195 |
82 |
1200 |
126 |
8 |
126 |
127 |
104 |
10 |
104 |
154 |
2400 |
64 |
16 |
64 |
252 |
58 |
17 |
58 |
277 |
4800 |
32 |
31 |
32 |
496 |
35 |
29 |
35 |
458 |
9600 |
17 |
60 |
17 |
962 |
23 |
43 |
23 |
682 |
19200 |
9 |
113 |
9 |
1816 |
18 |
56 |
18 |
902 |
38400 |
5 |
204 |
5 |
3261 |
15 |
67 |
15 |
1076 |
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Input (Analog L) |
Output (Analog S) |
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|
1 Channel |
16 Channels |
1 Channel |
16 Channels |
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Baud |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
mSec/ |
Chan/ |
300 |
639 |
2 |
2639 |
6 |
484 |
2 |
1984 |
8 |
600 |
323 |
3 |
1323 |
12 |
250 |
4 |
1000 |
16 |
1200 |
164 |
6 |
664 |
24 |
134 |
7 |
509 |
131 |
2400 |
85 |
12 |
335 |
48 |
75 |
13 |
263 |
61 |
4800 |
46 |
22 |
171 |
94 |
46 |
22 |
140 |
114 |
9600 |
26 |
39 |
88 |
181 |
32 |
32 |
78 |
204 |
19200 |
16 |
63 |
47 |
339 |
24 |
41 |
48 |
335 |
38400 |
11 |
91 |
27 |
602 |
21 |
48 |
32 |
494 |
It should be noted that the values in the preceding throughput tables and the following equations reflect only the communications overhead and inherent processing delay of the BASIC I/O equipment. In practice, a significant amount of overhead will be devoted to other processing tasks such as screen updates, data logging, etc. Typically these other tasks become the limiting factor in the "overall" throughput.
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The equations below can be used for determining the hardware's role in throughput for any number of channels (t is in milliseconds).
Throughput for digital I/O is independent of the number of channels. |
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|---|---|---|
Digital Input Data (Digital M) Time for 1-16 channels: |
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| tDigital Input = 1000 * ( ( 150 / Baud Rate ) + 0.001 ) | ||
Digital Output Execution ( Digital J ) Time for 1-16 channels: |
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| tDigital Output = 1000 * ( ( 110 / Baud Rate ) + 0.012 ) | ||
Throughput for analog I/O varies with the number of channels, n. |
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Analog Input Data (Analog L) Time for Channels: |
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| tAnalog Input = 1000 * ( ( ( 150 + 40 * n ) / Baud Rate ) + 0.006 ) | ||
Analog Output Execution (Analog S) Time for n Channels: |
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| tAnalog Output = 1000 * ( ( ( 110 + 30 * n ) / Baud Rate ) + 0.017 ) | ||
For determining the throughput for systems with a mixture of analog and digital data inputs and the execution of analog and digital outputs, it is necessary to determine the time for each instruction using these equations. The sum of these, t, in milliseconds, is the time required to provide the service required by all instructions. |
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| t = t Digital Input + t Digital Output + t Analog Input + t Analog Output | ||
Dividing this sum into 1000 (milliseconds) yields the number of cycles per second. |
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| Complete cycles/Sec = 1000/t | ||
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The BASIC I/O Communication Protocol is 100% compatible with the Opto-22 Optomux protocol. This ASCII printable serial protocol uses a "speak-only-when-spoken-to" format where only the Host can initiate an information exchange. Each BASIC I/O unit installed in a network has a unique address. This address is embedded in the instruction generated by the Host computer. Every BASIC I/O chassis receives the instruction but only the unit which is set to the address found in that instruction will respond. Every string of data whose length is greater than one character is followed by a checksum to ensure data integrity. This protocol also provides an instruction verification mode for further data transmission reliability.
As a result of the specific nature of the BASIC I/O communication protocol, the RS-422 or RS-485 network can be shared with other devices whose protocol is similar.
Knowledge of serial communications, hexadecimal to decimal conversion, and string data manipulation is required to compose custom user generated Host software. duTec's EASY I/O software is designed to minimize these obstacles.
Available I/O Modules
For our latest selection of I/O Modules, please see our module data sheet here.
To confirm internal operations and communication link integrity, a set of built-in diagnostics test key system functions each time power is applied. Diagnostics reduce both installation debugging and operation trouble shooting.
A hardware watchdog timer insures safe shutdown in the event of processor or software failures by turning all outputs OFF. Normally ON modules are available for these loads that must remain ON.
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Power Requirements: |
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Voltage: | 5.0 - 5.4V |
| Current: | 250mA + 25mA per digital module or 250mA + 200mA per analog module.
Note that the current draw of some specialized digital modules, such as the IDC5S or the ODC5R, can be substantially larger than 25mA. Consult the specific module data sheet for this value when sizing power supplies. |
|
| Operating Temperature | 0C to 60C (Contact factory for other operating temperature ranges) | |
| Humidity | 95% non-condensing | |
| Weight | 22 oz. Max. (BIO16) Not including modules. | |
BASIC I/Os are ready to install. Only power, communication, and sensor or actuator wiring is required.
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Every BASIC I/O is burned-in at 70 C while operating in a network for a period of 24 hours, prior to shipment.
Every analog I/O module is operated and tested while its’ ambient operating temperature is cycled over the specified operating range of 0 C to 60 C for a period of 24 hours.
BASIC I/O Models:
BIO4 |
4 Position BASIC I/O Unit
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BIO8 |
8 Position BASIC I/O Unit
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BIO16 |
16 Position BASIC I/O Unit |
duTec warrants its products to be free of defects in materials and workmanship for a period of two(2) years from the date of shipment. duTec may, at its option, repair or replace all materials found to be defective. All repair or replacement must be performed by personnel. Any parts determined by to be defective as the result of abuse, attempts to repair, or misuse by the customer will be repaired at the expense of the customer..
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