How do I Integrate SLC500 to Verbatim Gateway via DH485 over RS485 ?
This technical note explains how to interface the RACO Verbatim Gateway system with the Allen-Bradley MicroLogix family of PLCs via DH485. All but the earliest versions of MicroLogix processors that have the 8-pin mini-DIN integrated serial port, contain the DH485 protocol. This port, along with the 1761-NET-AIC, allows the Verbatim Gateway to perform its alarm notifications and monitoring functions using the existing wiring to the Allen-Bradley MicroLogix PLC as inputs via the DH485 protocol. This technical note is applicable for all Verbatim Gateway models.
Note: Not all MicroLogix processors contain the DH485 protocol. This tech note assumes the user is familiar with the MicroLogix processors that contain the required DH485 protocol.
In order to facilitate DH485 communications, RACO provides a serial cable that connects the Verbatim Gateway to the 1761-NET-AIC. This cable has the RJ-45 connector required at the Verbatim Gateway end, and the 8-pin mini-DIN at the end that connects to Port 2 (RS232) of the 1761-NET-AIC card.
|Communication Setup for the 1761-NET-AIC|
The 1761-NET-AIC provides DH485 connectivity to the DH485 network.
|Configuring the Allen-Bradley MicroLogix Serial Port|
In order to utilize the integrated serial port, setting the port Protocol to DH485 is required.
STEP #1 - Launch RSLogix 500 and open your MicroLogix File
Once your RSLogix 500 file is open, select Channel Configuration. This will launch the Channel Configuration form.
STEP #2 - Select DH485 Protocol
To set the serial port protocol to DH485, select the Channel 0 tab and go to the Driver pull-down menu.
Communication Setup for the Verbatim Gateway
The following seven-step procedure will configure your Verbatim Gateway to link its Remote Channels (RC) to your PLC addresses, via DH485. Once linked, the Verbatim Gateway will monitor RC status and Alarms according to your settings.
Connections to the PLC are via the onboard RJ45 port or NET. With the V232/485, two NET / ports are provided. NET ID = 1 is dedicated to the DH485 protocol and NET ID = 2 is configurable for either MODBUS RTU Master or DF1. (Refer to table #1.)
STEP #1 - Protocol Driver (4906)
When setting the Protocol, Node Address and Communication parameters, it is good practice to include the NET ID (i.e. 4901, 4903, 4904, 4905 and 4906). Insert the NET ID immediately following the parameter number, as defined below.
STEP #2 - Node Address (4905)
Choose a unique DH485 NODE address for the Verbatim Gateway. As illustrated above, we’ve already selected NODE / STATION 1 for the PLC. DH485 allows NODE addresses to range from 0-31.
STEP #3 - Communication Parameter (4901)
Select the communication parameters. These must match with the driver settings on your PLC. The only communication parameter applicable for the DH485 driver is 4901.
RACO recommends the following communication settings:
STEP #4 - Confirmations (4900, 4901, 4930, 4946)
Step #4 will validate all preceding steps:
STEP #5 - Set Defaults
This step simplifies Channel Configuration. (i.e. Step #6)
By setting to Default both the NET ID and NODE / STATION address, it is no longer necessary to reference them when setting Channel Configuration.
Set the following to DEFAULT.
STEP #6 Channel 1 & 2 Configuration (4501) (4502)
Now that you’ve mapped the ControlLogix Base tags to the SLC file type and since Verbatim Gateway channels are completely compatible with the logical and I/O addressing scheme for the file structure of the SLC series processors, the table below should look familiar.
Table #2 shows the Allen Bradley supported address types available to link to Verbatim Gateway channels.
The two examples below illustrate the link between the PLC data table (via DH485, Table #2) and the Verbatim Gateway channels.
To link the SLC mapped N7:0 register in the CompactLogix PLC to Channel 2 as per our PLC file structure illustrated above, key in the following:
STEP #7 - Assignment of Alarm Conditions
Having created and tested your Remote Channels, Step #6, you are now able to assign alarm conditions.
Channel #1, configured as Discrete, is either ON or OFF.
Channel #2, configured as Analog, operates within the range from 0-65, 535.
Should this channel be linked to a pressure signal in PLC, and the process requires that pressure remain within an acceptable level, otherwise ALARM, (For example, BELOW 10,000 AND ABOVE 30,000), we would key in the following:
Supporting Integration Notes: SLC™ 500 series PLC via DH485 over RS485