Sixnet offers a line of EtherTRAK remote I/O modules with Ethernet and RS485 communications. They come in wide variety of I/O populations. However, the EtherTRAK I/O modules are no longer recommended for new installations. The suggested replacement for this product line are the EtherTRAK-2 I/O modules.
EtherTRAK-2 offers superior performance at a better price per I/O point.
There are three groups of eight discrete I/O in this combination I/O module. Each of these three groups offers different capabilities to accommodate a variety of system requirements. A description of each of these I/O groups is given below. Refer to the Wiring Diagrams for further details.
First Group of Eight Discrete Inputs
The first eight inputs may be configured as sourcing inputs (ON when positive voltage is applied) or sinking inputs (switch closures to ground). There is a selection jumper in the module’s base that is easily accessed by unplugging the logic module and opening the hinged door. Select the desired mode – the factory default and most common setting is sourcing inputs. It is also necessary to make a similar selection in the Discrete Options window in the I/O tool Kit software. The module’s firmware performs a consistency check to verify that the hardware and software selections match.
The first group of eight inputs may also be modified to transition at a threshold voltage lower than the factory setting. This is accomplished by soldering a resistor into the base at the indicated location, according to the following chart. Please note that this resistor is only creating a reference voltage and therefore only needs to be rated for 1/8 Watt or less:
For this range:
Install this resistor
Standard range - no additional resistor required
Hysteresis – first
channel only (High
ON speed counter) resistor
Second Group of Eight Discrete Inputs
The second group of eight inputs is fixed as sourcing inputs (turn ON when a positive voltage is applied) with the standard 10 – 30 volt input range.
Third Group of Inputs/Outputs
The third group of eight discrete I/O has both input and output capabilities at the same time. Output functionality for a given channel may be individually enabled from within in the "Feature" column of the Discrete Options configuration window. For compatibility with I/O drivers that write I/O in fixed blocks, all eight Y (output) registers are always assigned. Only outputs that are enabled may be turned ON. Other output values will be masked in the I/O module.
Outputs may also be configured to function as TPO (Time Proportioned Outputs). These outputs turn on for a duty cycle that is proportional to the value placed in a corresponding analog output register. Refer to the upcoming description for more information.
All eight channels are always active as inputs. Channels that do not have their output function enabled may be used as inputs. For channels configured as outputs, the input functionality may be used to detect faults in the corresponding outputs.
Slow / Fast Response – Discrete Inputs
In the I/O Tool Kit software, select "fast response" to use minimal input filtering. DC input changes as fast as 5 mS will be detected. Selecting the "Slow response" setting will tell the module to look for stable inputs for approximately 25 mS. This setting will filter contact bounce, which often happens while counting mechanical switch closures in noisy environments.
Pulse, Rate and Runtime Counters
Eight counters are available and are associated with the first eight discrete inputs. These counters report their values in the corresponding analog input register (Sixnet address AX8 - AX15 or Modbus address 30009 - 30016). Counters are enabled by checking the " Enable Counters" box in the Discrete Options tab of the configuration window. Select the desired counter function for each counter in the "Range" column of the Analog (count register) options window.
The available functions include:
Up Count Count of OFF to ON transitions of the corresponding input
Run Time Sec Accumulated time (seconds) that the input has been in an ON state
Run Time Min Accumulated time (Minutes) that the input has been in an ON state
Seconds … Pulse Rate mode. Reports the number of pulses accumulated
1 Minute during the selected interval (from 0.1 second up to one minute).
Counters report unsigned 16 bit values (0 - 65535) and are volatile (forget their counts if power is lost). Typically, retention of the values and resetting the counts is accomplished in software at the host computer that polls these inputs.
The first two channels may be configured as high speed counters to record pulses as fast as 10 KHz. In this high-speed mode, the input filtering is not active, and even short input spikes will most likely be counted. Only select this option if (1) quick or frequent pulses need to be counted, and (2) the incoming pulse signals are free from noise.
A time-proportioned output is a discrete output that turns on and off in proportion to an analog value. Typically, the output will turn on and off once during the specified cycle time.
In this example, TPO #1 has a 10 second cycle time and the analog value is 3276 (10% of full scale, which is typically 32767). The output will be ON for 1 second and OFF for 9 seconds during each 10 second period.
TPO #2 has a 2 second cycle time and the analog value is 26214 (80% of full scale). The output will be ON for 1.6 seconds and OFF for 0.4 seconds during each 2 second period.
TPO #3 has a 2 second specified cycle time, an analog value of 820 (2.5% of full scale) and a minimum ON/OFF time of 100 mS. Since the minimum cycle time is 100 mS and the calculated ON time is only 50 mS, the cycle time is readjusted by a factor of 2 to maintain the time proportion. The output will be ON for 100 mS and OFF for 3.9 seconds before repeating.
Self-Resetting 4-20 mA Input Protection
Each 4-20 mA input channel has a 100 ohm, high precision (0.1 percent) shunt across its input to develop a 2 volt signal when a full scale 20 mA input is applied. These shunts are located in the module’s base, giving you the advantage of maintaining a continuous circuit even if the logic module is removed from the base. If excessive voltage is applied to an input, a self-resetting fuse will open to help prevent the shunt from overheating.
Open-Loop Detection on 4 – 20 mA Analog Inputs
This module can detect and report an open instrumentation loop on its analog inputs. By allowing the module to report a negative value if the current falls below 4 mA, low limit logic in your DCS, PLC, RTU or computer can signal the loss of current. To enable this feature, select the "Go Negative Below 4 mA" software setting for each channel.
Reading Voltage Inputs
As an option, a voltage divider may be factory populated to replace the 20 mA (100 ohm) shunt of one or more input channels. These alterations are made in the wiring base, so they may be tailored for particular installations. (The logic modules are not altered so they remain interchangeable!) Voltage operation may be configured in the I/O Tool Kit by selecting the appropriate range for the corresponding input. Consult Sixnet for ordering instructions.)
Initializing Communications (Getting Control of the Serial Port)
The default factory setting for the RS485 communications is 9600 baud, 8 data bits, no parity, one stop bit, Sixnet Universal protocol. Situations may arise in which the module is configured to communicate in a manner that is not compatible (or known) to the I/O Tool Kit software. It may be for example, that the module is configured at a baud rate that is incompatible with the computer's serial driver, or it may be configured for Modbus protocol. A feature is provided that will enable you to regain control of the port for maintenance purposes. First, highlight the module you wish to address. In the Operations f14 Advanced Operations menu, select "ResetSystemComPort". When you cycle the power on the module, the I/O Tool Kit software will trap the module as it initializes and reset the communications to the default factory settings. You may then perform the desired maintenance functions. Be sure to set the communications back to the necessary settings for system operation by using the Operations f14 load command.