Abstract
This document describes using the Isdeviceonline() function to detect comms loss and write zeros to tags.
Products
Red Lion Controls CR1000 Human Machine Interface (HMI), CR3000 HMI, Data Acquisition (DA10, DA30), Data Station Plus, FlexEdge™ (DA50A, DA70A), G3 HMI, G3 Kadet HMI, Graphite® Controller, Graphite HMI, Modular Controller, and Productivity Station™
Use Case
Write zeros to tags instead of the tags holding the last known value.
Required Software:
Crimson 3.0, Crimson 3.1 & Crimson 3.2
Crimson Communication Configuration:
1. Follow this tech note and set up a tag called CommsStatus using Isdeviceonline()function to detect whether the comms to the Modbus slave or any third party slave device is online or offline
Crimson 3.x: Detect Comms status – HMS Support Portal
2. Set up a gateway block to read the data from third party slave and send it to internal tags as shown in Figure 1. and Figure 2. below
Figure 1.
Figure 2.
3. Go to the programs section in Crimson database and write a program as shown below in Figure 3.
Figure 3.
4. In my example, I am reading data from Modbus RS485 Slave device and writing the data to internal tags so that these internal tags can then be mapped to another protocol for example DF1 Master (in my example). If comms go down, we will update DF1 Addresses to 0 instead of these DF1 Addresses getting the last reported Modbus value.
Figure 4.
5. Sample database is attached in this tech note.