### Analog Network Input 2 The information below provides a FULL description of this microblock and all of its properties. What information you see and what you can do with it depends on your license and the application you are in, and in some cases, a controller's driver version.
Microblock family | Network I/O microblocks
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What it does | Reads an analog value from a specific address on the network. Monitors and outputs the validity of network communication between the microblock and its target. You can address the microblock to read any network-visible I/O point value, status or parameter microblock value, BACnet object property value, or an equivalent value from a supported third-party protocol. The target value may be in the same control program, in another control program in the same controller, or in another Automated Logic® controller or third-party device on the network.
Click for details below How it works Properties Simulation Tips and tricks
#### How it works This microblock reads the value at the Address you specify. The target value can be a network-visible BACnet object property value or a third-party value (if the controller supports the third-party protocol). For a non-BACnet target, the microblock reads the target value at the interval you specify in the Refresh Time field. For a BACnet target, see "Polling or BACnet COV subscription" below. If communication with all specified targets fails, or if you uncheck Communications Enabled, the microblock outputs the Default value. If communication fails with the Address target, the microblock reads and outputs the Secondary Address target value. The Valid? output is False (Off) when communication with the Address fails. When the Valid? output is False, the microblock outputs the Secondary Address value if communicating, or the Default value if not. The Valid? output is True (On) when the microblock is communicating with the Address target value or when the microblock's present value is locked in your WebCTRL® or Field Assistant system. Polling or BACnet COV subscription If a Network Input or Total Analog microblock's Address field references a BACnet object property, the microblock reads the property's value using one of the following methods. Polling—The microblock reads the property at the Refresh Time interval using the BACnet ReadProperty or ReadPropertyMultiple service (see "Method 1: Polling" below). BACnet COV (Change of Value) subscription—The microblock subscribes with the target BACnet object. An analog target notifies the microblock if the target's value changes by more than the target's BACnet COV_Increment. A binary target notifies the microblock when it changes state (see "Method 2: BACnet COV subscriptions" below). Method 1: Polling
Benefits | Allows rapid detection of a dead device or of network problems Does not require additional memory
Drawbacks | Generates unnecessary network traffic if a value does not change frequently Misses value changes that occur between pollings Can overwhelm the target's controller if many microblocks request the same property value (such as outside air temperature). The BACnet object must send the value to each microblock that polls for that data.
To set up | Set the microblock's Refresh Time to 30 seconds or less.
NOTE The Automated Logic® microblock will not poll at a Refresh Time interval smaller than 1 second. BACnet ReadProperty and ReadPropertyMultiple services See the BACnet specification for details on the ReadProperty and ReadPropertyMultiple services. ReadPropertyMultiple occurs if: two or more microblocks in a controller read more than one target in the same remote controller, the Refresh Time in two or more microblocks expires at the same time, and the remote controller supports the service. Method 2: BACnet COV subscriptions
Benefits | Can decrease network traffic by preventing unnecessary updates if the target's COV_Increment is set appropriately. See step 2 in "To set up" below.
Drawbacks | Can generate excessive network traffic if the target's COV_Increment property is too small. See step 2 in "To set up" below. Can delay detection of a dead device or of network problems
To set up | Set the microblock's Refresh Time to 31 seconds or more. If the microblock's Address field references an analog property, set the target's COV_Increment property to the smallest amount by which the value must change for the target to notify its subscribers. The optimal COV_Increment is large enough to prevent unnecessary updates but small enough to be useful to the control program(s) receiving the updates.
NOTE If COV subscription fails, the microblock reads the value at the Refresh Time interval using the BACnet ReadProperty or ReadPropertyMultiple service. See "Method 1: Polling" above. COV subscription details When an input (Network Input or Total Analog microblock) subscribes with a BACnet target (object property), the input sets a 21-minute subscription Lifetime in the target. The target responds with a COV notification that includes the target's value and time remaining from the original subscription Lifetime (TimeRemaining). The input resubscribes with the target every 10 minutes to keep the target's BACnet subscription service active. The Next Subscription field on the input's Properties page shows the time remaining until the input's next subscription. The target also sends a COV notification that includes the target's value and subscription Lifetime TimeRemaining when the target's value changes by more than the target's COV_Increment. If the Automated Logic® target has one subscriber, the target sends COV notifications directly to that subscriber. If the Automated Logic® target has more than one subscriber, it broadcasts its COV notifications to optimize network traffic. A third-party subscriber can participate in this broadcast scheme by subscribing for Unconfirmed COV notifications with a Process ID of 0. Otherwise, the Automated Logic® target maintains and responds to the third-party subscription separately with its own Lifetime timer. The Automated Logic® input compares the TimeRemaining value in each COV notification broadcast the target sends to its (Next Subscription time + 11) to determine whether another input has subscribed since it did. If another input has subscribed more recently, the input adds 10 minutes to its Next Subscription time. This allows the COV Subscription request from the last subscribing input to keep the subscription service active for all subscribers to the same data. EXAMPLE
Elapsed time (minutes) | Action | Target Lifetime TimeRemaining (minutes) | Input 1 Next Subscription (minutes) | Input 2 Next Subscription (minutes)
--- | --- | --- | --- | ---
0 | Input 1 subscribes to target | 21 (Input 1) | 10 |
0 | Target broadcasts COV notification because Input 1 subscribed | 21 | 21 = 10 + 11, so keep current value of 10 |
2 | Input 2 subscribes to target | 21 (Input 2) | 10 - 2 = 8 | 10
0 | Target broadcasts COV notification because Input 2 subscribed | 21 | 21 > 8 + 11, so add 10 to current value of 8 8 + 10 = 18 | 21 = 10 + 11, so keep current value of 10
3 |  | 21 - 3 = 18 | 18 - 3 = 15 | 10 - 3 = 7
0 | Target broadcasts COV notification because value changed | 18 | 18 = 15 + 11 so keep current value of 15 | 18 = 7 + 11 so keep current value of 7
7 |  | 18 - 7 = 11 | 15 - 7 = 8 | 7 - 7 = 0 resubscribe
0 | Input 2 resubscribes | 21 (Input 2) | 8 | 10
0 | Target broadcasts COV notification because Input 2 subscribed | 21 | 21 > 8 + 11, so add 10 to current value 8 + 10 = 18 | 21 = 10 + 11, so keep current value of 10
Input 2 keeps the subscription service active at the target with a minimum of network traffic. NOTE If an input receives COV notification with a target TimeRemaining < 11, which could happen if the last subscribing input loses communication with the target, the input resubscribes immediately. COV notification rate COV notifications from a BACnet object property are controlled by that property's BACnet COV_Increment. When the absolute value of the difference between the property's Present_Value and the value sent in the last COV notification is greater than the COV_Increment, the object broadcasts a COV notification. For Automated Logic® controllers, the rate of notifications is further limited by two internal processes. The control program's execution rate determines how often the check against COV_Increment is performed. The controller's pending COV Notification task has built-in delays to prevent COV notifications from consuming the controller's CPU processing time. The built-in delays are as follows: If more than 15 COV notifications are pending delivery, the controller inserts a 50 millisecond delay after each set of 15 notifications. Once the entire list of pending notifications is serviced, the controller inserts another 50 millisecond delay. This results in a maximum COV notification rate of 300 COV notifications per second per Automated Logic® controller.
#### Properties TIPS Alt+click any value in the WebCTRL® or Field Assistant interface to view property details, including its editing privilege and expression (location path) for use on graphics. You can right-click some properties in the EIKON® Property Editor and select Make editable or Make read-only to determine that property's functionality in your system.
Display Name | The microblock label used in the EIKON® application and the WebCTRL® interface. You can use any characters except the " character.
Reference Name RefName | Use the default reference name unless you want a more descriptive name for graphics or network links. Limitations: lower case only limited to 40 characters cannot begin with a number must be unique within a control program
Lock Present Value | Check to output the locked value from the microblock instead of the microblock's calculated value.
Editing Privilege | Preset - Each microblock property has an appropriate privilege or role assigned to it. You can use Global Modify in the WebCTRL® interface to find out what the actual privilege is. CAUTION If you change the Editing Privilege from Preset, the privilege you select will be used for all properties of this microblock, which is not always desirable.
Display resolution | The microblock's value is truncated and incrementally updated as follows: The Display resolution format is used to truncate the microblock’s actual value. For example, if you enter a value from: 0.1 to 0.9, the system displays 1 digit to the right of the decimal 0.01 to 0.99, the system displays 2 digits to the right of the decimal 1 or greater, the system displays a whole number The Display resolution value determines the increment by which the displayed value is updated. For example, if you enter: .2, the system displays 8.4, 8.6, 8.8, ... .03, the system displays 5.09, 5.12, 5.15, ... 10, the system displays 30, 40, 50, ...
Address | The address of the target BACnet object property or third-party value (if the controller supports the third-party protocol). See To format a BACnet address or the applicable third-party protocol Integration Guide. This microblock reads a BACnet target's value using one of 2 methods depending on the interval you specify in the Refresh Time field. NOTE For a target in the Automated Logic® controller, you can specify the network microblock's Address in: Your WebCTRL® or Field Assistant system - Select the target in the tree on the microblock's Properties page Details tab. The system creates the address for you. The EIKON® application - In the microblock's properties The SiteBuilder application - If your product supports source trees and you are using them, SiteBuilder creates the address for you. NOTE You can uncheck the Editable field in the EIKON® Property Editor to prevent editing of the address in the WebCTRL® or Field Assistant system. TIPS If you are integrating to multiple identical third-party devices, you can copy the equipment for the first device and then let the system help you address the Network I/O microblocks in the copies. See "To create a control program for multiple identical third-party devices" in the BACnet Integration Guide. A single * (asterisk) as a device name in an Analog Network Input will initiate a broadcasted request for any device on the network that has MyObject to respond. The microblock will then determine which of the responders has valid data for MyObject and subscribe to that device. NOTE This syntax is valid when it is combined with an Object Name only. This syntax is not supported for Property or Priority and is supported for Analog Network Input and Analog Network Input 2 microblocks only.
Secondary Address | The address the microblock reads if communication fails with the Address field target. NOTE You can uncheck the Editable field in the EIKON® Property Editor to prevent editing of the address in the WebCTRL® or Field Assistant system.
Default Value | The value that the microblock outputs when communication with all specified targets fails or when Communications Enabled is not checked. The default value is used when the Valid? output is False (Off).
Communications Enabled | Check to enable network communications for this microblock. Uncheck when troubleshooting.
Refresh Time | The interval at which the microblock reads the target value. If the target is a BACnet object property: Type a value greater than 30 seconds to attempt a BACnet COV (Change of Value) subscription with the target object. If subscription succeeds, the target sends a value to this microblock only when the target's value changes by at least the target's COV Increment. If subscription fails, this microblock reads the target value at the interval you specify. Type a value of 30 seconds or less to disable BACnet COV subscription and read the target value at the interval you specify. If using v6.00a or later drivers, you can reduce network traffic by: Changing the refresh time to something greater than 10 minutes. If the refresh time is 10 minutes or less, the microblock will resubscribe every 10 minutes. If the refresh time is greater than 10 minutes, the microblock will use that value as the resubscription interval. Entering 01 in the seconds field of any value 1 minute or greater to have this microblock subscribe using only confirmed COV notifications (not unconfirmed). For example, 1:01, 5:01, etc.
Show Property Page Text | Check to show this microblock's value on the equipment's Properties page.
#### Simulation Define the value(s) the microblock will use when you simulate the control program.
#### Tips and tricks To address microblocks using source trees You can address a network microblock in the EIKON® application to target a microblock in its parent application on the source tree.
Format: Example: | exp:~equipment/~<source tree reference name>/~parent/~target/<target microblock reference name> exp:~equipment/~cool/~parent/~target/supply_air_temp
By using this format in the EIKON® application, the WebCTRL® application will read the target microblock value from the parent application. This method is much faster than going to each zone individually in the WebCTRL® interface to address the network microblocks. For example, this allows you to create generic zone applications that can be reused not only for all zones under a single air handler, but for all zones under any air handler. To speed detection of dead device If a BACnet object's device loses network communication, a network input reading the object's value does not detect the failure until the network input's next subscription (up to 10 minutes) if using BACnet COV subscription, or the Refresh Time expires, if polling You can use a small Refresh Time to poll more often, but this can generate unnecessary network traffic under normal conditions. To use the benefits of BACnet COV subscription, but overcome the potential delay in detection of a dead device, send a constantly changing value from the BACnet object's control program to a network input using BACnet COV subscription. If the value stops changing, the network input's control program generates an alarm. EXAMPLE The logic in the BACnet object's control program that sends the value. The BACnet Analog Value microblock has a COV Increment of 0.5. The logic in the network input's control program that receives the changing value. The SIGNAL analog network input's Address field contains the address of the BACnet Analog Value microblock sending the changing signal, and the network input's Refresh Time is 31 seconds.