Search results

Any Modbus slave has some means to set the slave address locally on the slave itself. There are mechanical means, like DIP switches or rotary switches (0-9). Or a slave ID setting done through a pushbutton/display HMI menu. Or a setting done using a utility program and comm cable used to...

I agree. I, too, found it difficult to locate how to ask a question (start a thread) - In the red menu bar at the top of the screen, click on 'Forums' - Select 'General Discussion' - At the top of the General Discussion page there is a red, 'Post New Thread' button link to that page...

Modbus is not plug-and-play. Modbus is a project. Congratulations, you're the project engineer! This document covers an overview of implementing Modbus in the field. It assumes that the devices have commercial Modbus functionality. If you are writing your own Modbus code, you need a...

I normally stay out of DCS opinion polls, but it’s apparent to me that the availability of local support should be a major criterion. There is little public forum support for DCS’s like there is for PLC’s, so the ability to get support from an ’authorized’ source, whether that’s factory...

which language? link to manual with Modbus information?

In post #1 you state: >Also I set modbus slave simulator at another computer and tested. It was successful. I interpret that as Modpoll on PC #1, slave simulator on PC #2. In post #13, you state >I just connected primary PC and bluelog only. I didn't connect slave simulator on a secondary PC...

Honeywell's LX that runs the C300 processor lists the time functions shown below. I assume PKS has those as well.

maybe a sketch would help . . .

There are commercial products made to address the problem of RS-485 star networks, like the one below. https://www.icpdas-usa.com/documents/I-7514Udata.pdf

"Using what's readily available." Boy, does that cover a lot. I think I've seen 4-20mA wired with everything in Ace Hardware's electrical department (except lacquer coated motor/coil winding wire): Zip cord (typically used for US lamps), Romex, bell wire (solid, non-twisted pair), speaker...

Agree, it seems like overkill. The home-run-to-JB is the longer run, isn't it? I2R voltage drop for 20mA is pretty low for a typical JB-to-instrument run, so I doubt was the consideration. But who knows?

The manual on the web is a 30 page light-reading feel-good brochure. What's the link to the comm manual that covers Modbus/TCP functions?

I can't answer your question but you should know that a 4 byte CRC will not work with Modbus RTU. And Modbus TCP strips out the 2 byte CRC because TCP handles the error checking.

You connected a Modbus Slave simulator on a secondary PC and talked to it with Modpoll on the primary PC, correct? That eliminates the PC firewall issue - Modpoll is getting through the PC Firewall. Can you take the PC with Modpoll and connect it locally to the field device (or bring the...

I forgot one - office grade (not industrial) Ethernet switch over heated when installed in an industrial control panel and failed at a temperature just higher than 40 Deg C, its rated temperature limit.

I am not a network guy and more than once it's taken a real IT/network guy to figure out what was blocking the Modbus comm. But I have encountered the following issues when troubleshooting Modbus over Ethernet. I'm sure some do not apply to you, but it's a list, so ignore anything that doesn't...

I sat through a sales presentation about 6-8 months ago on UOC. Here's my recollection on it. I would categorize the UOC as a mid-level DCS, easily equivalent to Emerson's Delta-V - both use rack mount I/O. 1. Redundant Comm? Honeywell's Fault Tolerant Ethernet (FTE), is quadruple...

You need some form of I/O that can handle your analog sensors: RH, Temp, and an AO. The I/O might well be stand-alone with a digital communication to your 'controller'. People like Opto 22 have I/O in various forms. RS-485 is just a hardware bus, it's the protocol (rules of communication...

No, someone else will have to advise you on the specifics.

The Rosemount 2051 low power transmitter (Output Code M) has a 3 wire 1-5Vdc output. The lower range output value, 1Vdc, is fixed, it cannot be ranged or shifted to zero. Your range adjustment has to be on the controller/receiver end, where for example, a 0-2.0 bar output over 1-5Vdc would...