How is PCX explorer installed and used on a PC?

Document ID

Document ID TE3849

Version

Version 3.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
How is PCX explorer installed and used on a PC?
Summary
Installing and using PCX explorer on a PC
Answer
The PCX Explorer is an OLE for Process Control (OPC) driver for Microsoft Windows® designed to easily connect 2200 PCX Particle Counters from Pacific Scientific to OPC clients. These clients can be SCADA (Supervisory Control and Data Acquisition) packages or any other application designed to connect to OPC servers. The Hach OPC Datalogger is included in the event a SCADA package is not available.
How Does OPC Work?
OLE for Process Control is a communication standard developed by the OPC Foundation®. OPC uses Microsoft COM technology to send Process Control messages between programs. This is the same technology used to link Microsoft Office® products such as Word™ and Excel™.
Fundamentally, OPC is comprised of two parts, servers and clients. Servers translate data from hardware devices and convert the data to a standard format called Tags. Each tag represents a piece of data such as a sensor reading, an alarm state, or a status value. The second part; clients, connect to servers and use the OPC tags to perform tasks Process Control tasks.
The Hach PCX Explorer is an OPC server. It communicates with the 2200 PCX particle counter and translates the data into OPC tags. The Hach DataLogger is an OPC client. It communicates with any OPC server, and logs data to simple text files. Multiple OPC Clients can access the same server at the same time. Virtually all 32-bit SCADA packages function as OPC Clients, allowing them to access data in a standard way.

Installation:
To start using the PCX Explorer, perform the following steps:
 
  1. Connect PCX network to the computer. A RS485 to RS-232 adapter is required to connect the PCX network to a computer. Follow these steps to connect the network to a computer.
  1. Connect the RS232 side of the adapter to the computer's RS232 Serial port. The ports on a computer are typically marked COM1 or COM2.
  2. Connect the other end of the adapter to the network as described in the users manual for the devices.
  3. Power up all networked devices you wish to communicate with.
  1. Start the PCX Explorer Program. To start the PCX Explorer OPC Server, click on the Windows Start button. Select Programs, Hach, PCX Explorer
  2. Discover devices. The PCX Explorer will discover all 2200 PCX Particle Counters on the network. OPC tags are automatically created and named.
    1. To begin the auto-discover process, click the wizard button or select Auto Discover from the Add menu.
    2. A dialog window opens telling you to connect all the PCX networks to the computer and start them.
    3. Once you have connected and powered up all the network devices, click the "Next" button on the dialog window.
    4. The next window shows the progress and status of the Auto Discover wizard. As devices are found they are added to the device list. The status bar indicates how much of the entire process has been completed. Indicators at the top of the dialog show how many possible device configurations have been checked and how many devices have been found.
    5. When all devices have been discovered, click on the "Finish" button and the devices will be added to the configuration. You do not have to click the "Finish" button. When the process completes, the wizard will automatically add discovered devices to the configuration.
 
4.Check the Configuration Setting.
A.To access the device configuration settings for the 2200 PCX select the device in the left pane of the PCX Explorer window. Right click the mouse and select the properties menu option.
B.The configuration window will activate which allows customization of the PCX device parameters including bin sizes and sample interval.
Configurations tab settings:
 
Name: A name that uniquely identifies the new device. This has repercussions on any OPC clients because the OPC clients will try to attach to an OPC tag using its name. If you change the name, any OPC Clients such as a SCADA may need to be updated to mirror these changes.
Sample Interval: This can be adjusted between 1 second and almost 1 hour (59 min, 59 seconds). The max counter value is 999999 or almost 1 million counts per sample. In raw water applications the counter will sometimes max its count value. Reduce the sample interval so that fewer counts per sample are collected. When the "Apply" or "OK" button are clicked, the program attempts to write the new counter interval to the device.
In Service: This check box allows you to take the counter out of service as needed. While out of service, the counter will not be polled for data and data quality for the counter tags will be set to Bad with the Out Of Service qualifier.
Address: The address of the counter is displayed but cannot be changed. To change the counter address you must use the special utility program PCX Setup or the SSU/CRTS program. Consult the users manual for using these programs.
Flow: The flow rate in ml/min thru the counter. This must be entered to correctly compute the normalized bin counts (counts per ml). There is no flow meter on the counter.
Data From Device: Poll the device for data.
Simulate Tag Data: Create virtual tag readings based on simulation parameters configured for each tag.
Port: The COM port used to communicate with the counter. The Baud, Parity... etc are fixed for the 2200 PCX
 
C.Bin Sizes Configuration. Click on the "Bin Sizes" tab of the Device Properties dialog to activate the Bin Size configuration window. Normally bin sizes will be 2 to 20 microns. However, sometimes in research, bin sizes need to be higher. The maximum bin size allowed is 999. Calibration points to support the selected bin sizes must be downloaded to the 2200 PCX manually using the CRTS utility. Hach provides calibration points for bin sizes up to 20 microns. Additional calibration points for larger values may be purchased from Hach for a small fee. The 2200 PCX protocol supports 3 characters of resolution for bin sizes. Bin sizes less than 10 microns are allowed to have 1 significant digit after a decimal. For example 2.5 or 7.8. For sizes larger than 10 microns, the protocol will not support fractional bin sizes because of the lack of characters to transmit the decimal value. For example 10.2 will not work because it is 4 characters in length.
D.Analog Inputs. This window allows you to quickly change the min, max and dead band values for the tag output. Additionally the analog input can be enabled or disabled. If the analog input is disabled, the PCX Explorer program ignores data from the analog input. To actually disable the input on the card use the CRTS utility supplied by Pacific Scientific. Additional tag settings can be accessed by clicking on the "More" button or selecting the tag properties manually. The dead band percent defines the amount of change of full scale required before the new tag value is sent to clients. This feature can be used to eliminate noise in the readings, which generates extra load on the CPU, network and database of the client SCADA. As noted in the window, the analog inputs are only available if the analog accessory card (57001-00) has been purchased and installed in the counter. The 8 analog input channels can be enabled or disabled on the card using the CRTS utility.
E.Calibration points. Calibration curve points that are currently loaded into the instruments will be displayed in the Cal curve window. Click the tab "Calibration Curve points" to activate the window. These values are read back from the instrument at device initialization time. This happens the first time an OPC Client requests data from this device or when the data value monitor is enabled in the Server (Monitoring Tag Values). The calibration curve points must be downloaded to the 2200 PCX using the CRTS utility provided by Pacific Scientific. This utility is installed into the Hach program folder when the OPC Server software is installed. To download calibration points, the device must be power cycled and a special configuration command sent within 30 seconds of power up in order to activate the special mode that allows the calibration points to be changed. More information can be found in the instrument manual.
 
 
  1. Monitor the tags to ensure the system is working
A.Polling A Device. To start polling on a specific device, select the device in the left window pane, then click the toolbar button to start polling, or select the menu item Poll | Start Polling. When polling is active on a device, the menu item will be checked.
Stop Polling A Device. To stop the device polling that was activated from the OPC Server user interface, select the device in the left window and then click the toolbar button to Stop polling the selected device. The Poll menu item Poll | Stop Polling can also be used to stop the polling Polling Status