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accessing measured values from PAC3100

Created by: srk at: 11/30/2010 2:43 PM (4 Replies)

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11/30/2010 2:43 PM	Rate (0)
srk Posts: 8 Rating: (1)	hi, I have connected PAC3100 to a third party modbus controller (Rockwell, compactlogix - L32E with Modbus communication module 1769-SM2) All the unsigned long values from PAC3100 are being accessed and we are able to "read" the values on the screen and relate them to the actual values. for e.g. baud rate, primary voltage etc. But all the measured values (float) like voltage a-n shows up split into two values (in two tags) for e.g. for a value of 198 V approx the corresponding value that we read is Tag 1: 17213 (constant most of the time) But Tag 2: shows 7204 then 21677 then some negative value. We are unable to decipher the float type data. Can somebody help?
srk Posts: 8 Rating: (1)
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11/30/2010 3:04 PM	Rate (0)
Robster Gold Member Joined: 5/28/2008 Last visit: 10/23/2024 Posts: 1343 Rating: (141)	Hi, I don't know the rockwell controller. But with siemens controller you have to declare, what type of data you want to receive (word, dword, floating, ...). If floating is selected, I will get same problem like you have. I will get a word-value into a floating variable. So I think you have two possibilities. 1. declare word-type for all received datas and build up your float and dword values manually with "AND" or "OR" instructions. 2. declare same data type like in PAC and read out different data types with different steps. So you have to read out the PAC for example two times. One time for float, one time for dword or anything else.

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12/19/2010 9:49 PM	Rate (0)
rynite Posts: 50 Rating: (6)	Hello, The SENTRON PAC3100 meter is standard Modbus RTU Server Client model. And the 3100 works as a standard Modbus server. The meter is designed in accordance to the modbus application protocol specification V1.1b. Please look to the attachtment there you can find the application protocol. Telegramm desciption: 1. Bus Adress (1Byte) 2. Function code (1Byte) 3. Data (2 Byte) Example to read voltage PH L1-N (Client with bus address 1) 01 03 00 01 Attachment Modbus_Application_Protocol_V1_1b.pdf (748 Downloads)
rynite Posts: 50 Rating: (6)
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10/9/2011 3:25 AM	Rate (0)
srk Posts: 8 Rating: (1)	Hi, Thank you we were able to build the float value swapping the registers at the PLC. With this we could read all the Float data types like, Voltage, current, power etc. We have a similar problem reading the Active Energy and Reactive Energy. We see 5 values at the PLC unable to arrive at the value shown on the display of PAC3100 PAC3100 connected to Rockwell Compactlogix Controller. Attached is screenshot showing the values in the PLC. Corresponding Reactive Energy: 216892.15 kvarh 1) Why are 5 values appearing when we have defined 4 registers to be read starting from 805. 2) How do we arrive at the actual Reactive energy Can somebody help? Attachment plc program screenshot-1.pdf (707 Downloads)
srk Posts: 8 Rating: (1)
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10/9/2011 3:30 AM	Rate (0)
srk Posts: 8 Rating: (1)	The code used for deciphering the actual float values is attached for reference: A similar code may be required for arriving at the Active Energy and Reactive Energy values. But it seems it is not so easy, as the code for arriving at correct float values. Attachment RSLogix 5000 Report(s)-MFM.pdf (695 Downloads)
srk Posts: 8 Rating: (1)
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