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I think the situation is that the HMI panel, a MODBUS master, is polling the drive, a MODBUS slave, and is causing a error/fault. It is not clear whether Modscan can read data from the drive successfully or not. What is the result of Modscan reading the drive? "I tested it but its working...

I suspect RS-485 will work at longer distances than the usually cited maximum 1200m (at low baud rates) from 2 different farther-than-the-spec non-485 experiences. One experience involved a half duplex, no handshake 3 wire (Rx,Tx, Gnd) RS-232 link with the usual 50ft (15m) distance...

The troubleshooting manual is at this link: https://www.emerson.com/documents/automation/maintenance-troubleshooting-manual-3410-series-gas-ultrasonic-flow-meters-daniel-en-44122.pdf, but has no mention of 4-20mA. Most 4-20mA devices have a fault mode at some level below 4.0mA or above...

Welcome to the wild west world of Modbus. Since Modbus is an open protocol (you can download the specs from the web and being truly open, you don't have to pay for the spec, unlike other 'open' protocols), but the downside is there are no Modbus police so Modbus depends on its implementation...

Possible reasons for magmeter fluctuations - conductivity lower than the minimum required by the flow meter to get a reliable reading (depends on how de-mineralized the water is) - vertical down flow (attempted) measurement - entrained air - remote transmitter mounted remotely and...

I've been pondering this over the past couple weeks. I still think that the installed 3-wire configuration is producing a ground loop. Both the installed 3-wire wiring device and the mfg's current 2-wire spec sheet use the same model number. I think it strange that an updated model would...

If you are truly sending the same 'forced' value (same bit pattern) with the same command from the master, then a misinterpretation of the value (due to mis-interpretation of the data format) on the HMI would be displayed as an incorrect value, but that incorrect value would remain constant, it...

The master/client's command has not been fully executed. The reasonable expectation of writing all values to valid registers is not accomplished. The slave should send an exception to either or both cases, ignore the message and change nothing in its slave registers. The steady stream...

>two different IP networks. Presumably, you mention RS-485 because the PLCs each talk Modbus RTU over RS-485. An RS-485 port is not concerned with IP (Ethernet) addresses. >Now there is a need to share data across these two PLCs. Which are separated by >1.5km distance. Can I achieve it...

I made a mistake above because I learned to start counting with the number 1, not with the number 0. Registers 0000 through 0010hex (16 decimal) total 17 (decimal) because register 0000 counts, too. So the reply should have 34 sets of double question marks for 34 bytes of data from the 17...

In your query: * the first byte is the slave node ID, 0f hex or 15 decimal * the 2nd byte is the function code 03, read holding registers * the 3rd and fourth bytes are starting address 0000 * the fifth and sixth bytes are the quantity of registers 0010 hex or 16 decimal * the 7th...

Have you considered alternative materials? A teflon tube (to prevent build-up) inside of a hastalloy tube? Here's ABB's materials chart. Check out brine at the bottom: https://i.postimg.cc/jjJQMCZg/ABB-xmtr-material-chart-brine.jpg

The dated appearance of the first wiring diagram I found (on a distributor web site) spurred me to check Monitran's factory web site. Monitran's factory site has what is presumably the current model 1185 spec sheet which shows a conventional 2 wire loop powered 4-20mA accelerometer, not the 3...

I'm surprised that no A-B/Rockwell guys have jumped in yet. I know Rockwell has a "Partner" that sells the Loop-Pro Tuner software. https://controlstation.com/rockwell-tuner/ The partners generally do stuff Rockwell doesn't, so I doubt that Rockwell's standard development software...

>>Last question - what brand/model are these seismic eddy current probes? >Monitran MTN 1185 The link below shows the wiring diagram for a Monitran 1185, taken from a spec sheet on the web: https://i.postimg.cc/28R3xtQ6/MTN-1185-wiring-diagram-0-V-common-is-labeled-screen.jpg It's 3...

Are either the DCS xmtrs or the seismic probes on Intrinsic Safety (I/S) barriers? If so, passive I/S barriers or active (I/S) isolators?

To summarize the situation as reported: (If incorrect, please correct.) There is a Bently Nevada 3500 vibration system. The Bently Nevada system runs OK. It is not part of the problem. There are additional seismic eddy current probes that are powered by and connected to the DCS, but are...

earlier discussion involving the practicalities of the multi-vendor Modbus world shed some light on the topic: Calculating the character gap http://www.control.com/thread/1299632001 Lynn L's insight: https://modbus.control.com/thread/1026182146 Delay between polls...

Technically, the master first asks for data, and then the slave (the energy meter) replies. Modbus slaves can not initiate a transaction - cannot send on their own. The problem could be almost anything - Devices must be Modbus enabled. Just because a device has a serial port does not...

I don't know what functionality the listed model numbers represent; whether they're even Modbus capable or if they run some other protocol. But if the existing network is a Modbus network and the network is Modbus RTU over RS-485, then your IoT device would be 2nd master on the network, which...