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- Windows, real time
- PID loops
- PCs vs. PLCs
- Replacing people
- MS 'monopoly'?
- Software quality
- Where do we go from here?
- Why pay?
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Member Information and Posts by Harvard
Return strings from Modbus simulator application differ from that of HVAC system harware
New Replies:
It is not unusual to have byte reversal issues. One of the devices, Host or Slave, should have a...
Convert SIMATIC to MODBUS address
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To poll Address 11, Reg 40001 for 2 Regs:
0B 03 00 00 00 02 C4 A1
To poll Address 12 register...
Can I use the Modbus frame size larger than 256 bytes?
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No! If you notice in the Function Code 3 slave response the 3rd byte is the byte count of the data...
how a flow meter communicate
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I think you are saying you need to convert pulses from the flow meter to an accumulator that...
How many slave devices cab be multidroped on RS-485 bus?
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The Master is just another device, so 32 including the Master is your correct answer. Remember, the...
from the PLC Communication/Running Status department...
Momentum/ 984/ Premium PLC's - how do I monitor the Modbus Plus link light status and Running status in WW InTouch?communications monitoring on PLC's
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The most common method of making a "Watch Dog Timer" is to have a Modbus register...
Error in reading Analog Data from Holding registers
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1. Parity is redundant with CRC checking, so you might disable parity else you may limit full...
What is the MODBUS RTU PROTOCOL format for ODD PARITY?
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Parity is redundant and never normally used WHEN CRC error checking is implemented. Parity is not...
Modbus adaptor
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I think you are asking for a ModBus Slave Simulation application that will respond to any ModBus...
Does a MODBUS AI (MAI) make sense??
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Modbus has Holding Registers and Input Registers. You cannot write to a Input Register, it is for...
How long can the taps on a modbus network be and are you limited to the amount of taps for 32 devices?
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RS485 2 wire 1/2 duplex cannot have any "Tap length". There are only 2 ends to an RS485...
a question about modbus function codes, as well as looking for help with micrologix1400
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Modicon Register 40001 is Modbus Register 0.
The correct poll is:
01 03 00 00 00 02 C4 0B
...
TCP slave with sepparated memory maps
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>//2b. Prepare a process image from 45001 to 45100 spi.setRegister(45001, new...
PLC Modbus Master will not talk to SATEC power measurement meter.
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I have a freeware Win32 Console application that will monitor two RS232 1/2 duplex data streams...
Are there different dialects of Modbus?
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While there are variations I have never seen something as you describe. Here are two write...
Do you recognize this error checking?
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Yes it is a 0x64, here are a few more from the same com link.
f0 01 00 02 00 01 01 7e 9a
f0 15 00...
I need to use a special hardware?
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If your LapTop has an RS232 port and the Modbus device also has an RS232 port then no converters...
connecting multiple devices to modbus over rs-232 by using RS-232 to RS-485 converter
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According to the Gould Modbus Protocol Reference Guide PI:MBUS-300 Rev B, a Function Code 7 has a 4...
There is a cheap and dirty method of connecting multiple RS232 slaves to one host using RS232 if...
See bb-electrocics.com for lots of good info on RS232 to RS485 converters. A good choice is their...
Is there any 3rd party tool s/w available in the market to pinpoint the type of failure in commn. from a particular slave?
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If the moderators allow this to post, I have a freeware WIN32 Console application that will monitor...
Most intermittent Half Duplex COM errors are either associated with RS485 GND issues OR Timing...
modbus analyzing from the outside
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Most likely caused by timing settings. I would verify the Slave "Turnaround Time" setting...
A few questions regarding the coding system of modbus RTU
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>My 1st question:
ANS: For RTU mode there is No Parity. RTU mode uses CRC error checking. An...
Problem connecting 2-wire modbus RS-485 to 3-wire Modbus RS-485 on daisychain modbus network.
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Start with the MOXA 3180 and add one slave at a time. Do not be suprised if the Data+ and Data-...
Variable mapping
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I would use a C code "union" to accomplish this mapping, if I get your drift....
Problems talking to a slave machine using the Modbus RTU protocol.
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You will not get a response from a Modbus slave if the CRC is in error, it will be assumed to be...
from the Double Register Data Polling department...
Siemens Sentron PAC3200 Power Meter Energy Readings
How can I retrieve the energy reading from Siemens Sentron PAC3200 power meter which is Double Register format?
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These double registers are most likely IEEE Single Precision numbers. As such, they will be sent in...
Can only read 6 registers from Controlotron 1010 flow meter via Modbus
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If this connection is Modbus RTU protocol then you would not want to be using parity and 7 bits....
Trying to read Reg 400001 from a Adams 5000E to a elpro 905u-G
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>So should i set the radio to read register 40001 or just 0?<
Probably 40001 and it will...
Modicon Register 400001 is a misprint, should be Modicon Register 40001 which is polled as ModBus...
Data from the NOC is not resetting between tests.
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Probably a timing issue, as in a race condition, associated with a fast communications connection....
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