This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
|Try our online
PLC Simulator- FREE.
Click here now to try it.
New Here? Please read this important info!!!
|December 2nd, 2009, 03:22 AM||#1|
Join Date: Jun 2008
Omron Modbus PMCR
I have the Omron CJ1M CPU and SCU31-V1 module for Modbus with Protocol Macro using PMCR instruction in the ladder. Here PLC is the master and Remote I/O cards are slaves. We have 13 Remote cards/slaves.
Is any other method for Modbus PMCR polling other than using a counter?
Time b/n polls or pollrate on a slave in 13 slave network is 1.5sec. I want to reduce this time.
Last edited by lakshmi.chamarthi; December 2nd, 2009 at 03:24 AM.
|December 2nd, 2009, 08:40 PM||#2|
Lifetime Supporting Member
I use a counter for this always.
There are 3 things that slow down polling - number of devices - size of poll and comms speed. Increase the speed and decrease the time - decrease the number of polls and decrease the time - decrease the size of the poll and decrease the time.
I normally poll a maximum of 4-5 devices at a minimum speed of 19,200 baud. I find it is quicker to do 2 polls to a device sometimes. If I want 3 words from one area and 3 words from another area it is usually quicker to do 2 polls for the 3 words each time than poll 50 words top get the same information in one block with a lot of other rubbish.
The SCU31 has 2 x RS485 - break the network into 2 and use both ports.
The Old Pfhaart
|Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)|
|Thread||Thread Starter||Forum||Replies||Last Post|
|Omron CQM1H With Modbus Comms||JPM1||LIVE PLC Questions And Answers||2||November 4th, 2008 09:17 AM|
|Omron E5CN modbus firstname.lastname@example.org||LIVE PLC Questions And Answers||0||August 6th, 2007 06:23 AM|
|Omron 3G3RV drive Modbus||djpalaz||LIVE PLC Questions And Answers||1||March 1st, 2007 10:36 AM|
|Mitsubishi Q Series Modbus TCP module QJ71MT91 set up help req'd...||Pocko||LIVE PLC Questions And Answers||0||July 30th, 2006 02:45 AM|
|MODBUS RTU master for Omron CPM2||mempson||LIVE PLC Questions And Answers||1||February 21st, 2006 11:15 AM|