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FB108 inputs and start address

Created by: a.z.r at: 6/28/2014 10:15 AM (3 Replies)

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6/28/2014 10:15 AM	Rate (0)
a.z.r Bronze Member Joined: 6/8/2013 Last visit: 10/1/2024 Posts: 188 Rating: (1)	hi all i work on one project that s7-300 is client and tsx premium plc is server.....there was a input with name START_ADDRESS in FB108(modbus cp) ..... this start_address refer to which DB? thank you

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7/1/2014 11:59 AM	Rate (0)
Sakura Silver Member Joined: 9/22/2010 Last visit: 7/25/2024 Posts: 225 Rating: (28)	Hello a.z.r, the START_ADDRESS refers to the first Modbus address that you want to read/write with your next telegram.Before you trigger a Modbus request by setting ENQ_ENR, you have to provide the runtime parameter START_ADDRESS, UNIT, DATA_TYPE, LENGTH and WRITE_READwith proper values. The mapping between the Modbus addresses and the DBs in which the data is stored is already done during the initialisation in OB100. This means during runtime the Modbus block knows in which DBs the Modbus data is stored. Regards, Sakura

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7/4/2014 11:39 AM	Rate (0)
a.z.r Bronze Member Joined: 6/8/2013 Last visit: 10/1/2024 Posts: 188 Rating: (1)	hi MR.sakura thanks for answer do i use 2 modbuscp block in ob one if i want to read several holding registry and coil ?

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7/4/2014 11:50 AM	Rate (0)
Kaulquappe Posts: 3093 Rating: (323)	Hello a.z.r. No!!! Just have a look at the online help or the manual, there is clearly stated: FB108 must be called ONCE in OB1. The sample project shows how input parameters can be changed. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (323)
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