Dear sir

Today, I was trying to communicate a modbus device with S7 1500N PLC via CM PtP RS232 HF Module.I am not getting any modbus values.Please help.

Problem#1: I am not getting Modbus_Comm_Load - Done bit high.

I have attached Comm_Load network picture.First Scan Cycle bit is not getting high.

I have enabled it in CPU properties. Memory bit M1.00 is used for other purpose.Hence I used M200.0 as assigned 200 in CPU Properties.

Also always True & False bit not working

What is the possible reason comm _Load Done not getting True?

Why First scan bit not getting True at first cycle?

Test carry out: I have connected this bit in series to a coil and coil NO contact connected in parallel with First Scan Cycle NO contact as a holding contact.It's similar to Motor starter diagram.But coil is not energizing.

Problem#2: Modbus Master not getting Done True, Error & Busy getting True and False

Status: 16#7001, & Error #8281

What is the reason for ?

How to solve it?

Port parameters checked in Comm_Load-OK

Bound rate-19200

Parity-0

Stop bit-1

HW Port-276

Solution tried:

I have checked forum, moved 0(for RS232) to Comm_Load.Mode-Not worked

#Problem:3- CM PtP RS232 HF interface module shows Red LED blinking.Diagnosis shows Wire break.I could not find any wire break.rs232 Port and modbus device connected well.

How to solve it?Why do it shows Red LED blinking?

Diagnosis report attached below in next comment.

Modbus device-Tyco CCU3

Please help

Problem#3: Diagnosis report attached.

 Wire break??

Thanks for reply.

I am waiting at site to solve these issues and commission the system.

How to check Comm_Load_Done bit was high at first scan cycle?

What is the solution for  16#8281 error?

Please check diagnostic report in above attachment. Why CM232 shows System fault Red LED blinking???

Please help

Dear sir

Thanks for reply.

I got it from Modbus_Com_Load DB

Is it WRREC?

How/What to check here when PLC online?

How to ensure Com_Load giving Done bit True at first scan cycle?

Duris_I

Hello jibemathew,

I see your system of implementing as not correct, especially that conditions are not logical to me. Again, you need use SET coil -> --(S)-- to be sure your Comm_Load is DONE correctly. As I see this:

1. you permanently run Comm_Load cyclically, this can be problem especially with some version of blocks.

2. I don't see any error status of Comm_Load block, also not error so where you have that 16#82xx status? Look, generally rule is, if you don't have correctly executed Comm_Load block, you can't use Master block. If this is true (you need post infos) pls attach all informations.

3. Pls attach zipped screenshots, also with CM RS-232 to see that HW ID what you have in Comm_load configured but I see problem probably with Master block executed without correctly Comm_Load block finished.

3. What device you have connected as Slave?

Your question with no data is very quickly posted, to have correct data from Slave device you need configure correctly more steps as you have posted here till now, sry.

Update: MOP, I see your good description about WRREC but this block is little bit hard for him to understand  I think he need continue with Comm_Load correctly execution and then experiment with Master block, as general rule...

I have attached screenshot of program.

Please check it tell me a solution.

I am unable to set a bit with Modbus_Com_Load_Done

I have a doubt first scan cycle bit become true at scan first cycle

I am getting errors/status #8182, 7001,7002

Duris_I

Hello jibemathew,

I see your system of implementing as not correct, especially that conditions are not logical to me. Again, you need use SET coil -> --(S)-- to be sure your Comm_Load is DONE correctly. As I see this:

1. you permanently run Comm_Load cyclically, this can be problem especially with some version of blocks.

2. I don't see any error status of Comm_Load block, also not error so where you have that 16#82xx status? Look, generally rule is, if you don't have correctly executed Comm_Load block, you can't use Master block. If this is true (you need post infos) pls attach all informations.

3. Pls attach zipped screenshots, also with CM RS-232 to see that HW ID what you have in Comm_load configured but I see problem probably with Master block executed without correctly Comm_Load block finished.

3. What device you have connected as Slave?

Your question with no data is very quickly posted, to have correct data from Slave device you need configure correctly more steps as you have posted here till now, sry.

Update: MOP, I see your good description about WRREC but this block is little bit hard for him to understand  I think he need continue with Comm_Load correctly execution and then experiment with Master block, as general rule...

I have attached screenshot of program.

Please check it tell me a solution.

I am unable to set a bit with Modbus_Com_Load_Done

I have a doubt first scan cycle bit become true at scan first cycle

I am getting errors/status #8182, 7001,7002