Rheonics measurements in tank inventory hosts via CIU 888 OPC UA Print

TABLE OF CONTENTS

• 1. Overview
• 2. Configuring the CIU 888 Modbus field port
• 3. Configuring the CIU 888 OPC UA TCP host port
• 4. Connecting ENTIS or another OPC UA client
• Related articles
• References

1. Overview

The CIU 888 configures field side and host side connectivity separately (Figure 2):

• Field side. The CIU 888 acts as a Modbus RTU master over RS‑232 or RS‑485, polling third party Modbus RTU devices such as the SME (Layer 1).
• Host side. The CIU 888 exposes the collected and calculated tank data as a Modbus TCP/IP server or an OPC UA TCP server on its Ethernet host ports: FTEA, FTEB or Office LAN (Layer 3). Host systems such as Honeywell ENTIS, Experion PKS or third party tank inventory software connect as clients [1].

The SME is available in three variants (Figure 1). All three carry the same Modbus RTU registers, so this article applies to any of them; the variant only changes the installation.

2. Configuring the CIU 888 Modbus field port

Field port and site configuration is done in the CIU 888 Service Tool. The Rheonics SME is not one of the device types built into the tool, so it is added as a new Modbus field device type through an XML device configuration file, imported with Import MODBUS device type file on the CIU 888 node. Once imported, a Modbus Data Input on the tank can reference it [2].

• Register address format. The CIU 888 uses a six digit Modbus Register Address. The leading 3 marks an input register and the remaining digits are the SME register address plus 1, so SME address 48 becomes 300049.
• Data type. Viscosity, density and temperature are Float32 values (IEEE 754, big endian) spanning two consecutive registers [5].
• Viscosity units. The CIU 888 device template has no native viscosity unit type, so viscosity is carried as DeviceUnitType = ANY, without unit conversion. Any unit handling happens in the host application.

Table 1. SME registers mapped to the tank in the Modbus Data Input

3. Configuring the CIU 888 OPC UA TCP host port

Once the SME values are live on the field side, they are exposed to host systems by configuring an OPC UA TCP host port on one of the CIU 888 Ethernet interfaces.

• Interface. OPC UA TCP is configured per Ethernet host port (FTEA, FTEB or Office LAN). Office LAN is the usual choice when the tank inventory host sits outside the redundant FTE network.
• Protocol and port. Set Protocol Type to OPC UA TCP and confirm the OPC UA server is enabled on that port. The default server port number is 51000 [2].
• Security. Select the security policy and message security mode required by the site, and set up the server certificate as self signed or CA signed [2]. Only OPC UA TCP is supported; OPC UA over HTTPS is not [2].
• IP address filtering. If IP address filtering is enabled on the host port, add the IP address of the tank inventory host to the allow list.

4. Connecting ENTIS or another OPC UA client

Honeywell's ENTIS tank inventory system connects to the CIU 888 over OPC UA to read the tank records with the inventory data of each tank [4]. Any other OPC UA client connects to the same server in the same way.

• Endpoint URL. The endpoint follows the pattern opc.tcp://<CIU_888_IP>:<port>, for example opc.tcp://192.168.20.10:51000 [2]. Use the port configured on the host port in Section 3.
• Security and certificates. The client security policy and certificate must match the CIU 888 configuration (self signed or CA signed), with credentials supplied if anonymous access is disabled.
• ENTIS node. For ENTIS, each tank exposes a dedicated ENTIS node (CIU888.Tanks.[TankName].ENTIS) that carries the tank record and temperature profile record as a single JSON object [3].
• Where the SME values appear. The SME values are exposed as the tank parameters they were mapped to in Table 1, under that tank in the CIU 888 address space. Browse the server with an OPC UA client such as UaExpert to confirm the node names before configuring the production host.
• Other clients. The same endpoint, security policy, and information model apply to UaExpert for verification, and to Experion PKS or a third party tank inventory host in production.

Related articles

References