Hello Experts,

I have a system, where Honeywell's new C300 Experion PKS - Profibus Gateway Module - PGM is connected to 6 PLC stations via Profibus - DP Loop.

PLC is S7300 - and it has its own IO cards. The PLC is configured as a device in PGM module - similar 6 PLC are connected in a Profibus - Daisy chain fashion. DCS is acquiring AI/AO/DI/DO from each PLCs.

We are required to change the PLC configuration - meaning, few field Limit switches will be converted to 4-20mA Transmitters - accordingly PLC cards will also change. PLC Vendor will take care of this modification. In this situation my questions are as below:

a) Will DCS get a new GSD File from Siemens PLC vendor?

b) Modification will happen - one after the other - so, is it possible to upgrade a single slave device in Honeywell PGM Profibus loop? Keeping the other 5 device intact and working normal.

c) Considering all the 6 slaves are connected in daisy chain, how can we disconnect one PLC slave without affecting other 5 slaves?

Your valuable insights will be really helpful.

Thanks in Advance.

Rajesh K.

 Hello rajesh;

First, I need to point out that I have no experience with Experion systems, ther Profibus configuration tools and programming software. However, I am familiar with Profibus-DP networks and certain procedures are similar, whatever the Profibus configurator.

rajesharihant

Hello Experts,

I have a system, where Honeywell's new C300 Experion PKS - Profibus Gateway Module - PGM is connected to 6 PLC stations via Profibus - DP Loop.

PLC is S7300 - and it has its own IO cards. The PLC is configured as a device in PGM module - similar 6 PLC are connected in a Profibus - Daisy chain fashion. DCS is acquiring AI/AO/DI/DO from each PLCs.

We are required to change the PLC configuration - meaning, few field Limit switches will be converted to 4-20mA Transmitters - accordingly PLC cards will also change. PLC Vendor will take care of this modification. In this situation my questions are as below:

a) Will DCS get a new GSD File from Siemens PLC vendor?

There should be no need for a new gsd file for the S7-300 slaves; however the programmer will have to modify the input/output areas used by the S7-300 CPU so as to take into account the address areas for the new analog modules in the data exchanges with the Honeywell master. The configuration for these exchanges will also have to be changed in the C300 PGM master module, everytime a slave connection is modified.

Siemens Support proposes a sample configuration of a S7-300 as Profibius-DP slave with a S5 as master (you can consider the S5 as a 3rd-party Profibus master in this case). This should explain the principles of configuration involved:

How do you operate an S7-300/400 as a DP slave on the PROFIBUS DP when the DP master is an S5 (with IM 308-C)?

https://support.industry.siemens.com/cs/ww/en/view/6709721

b) Modification will happen - one after the other - so, is it possible to upgrade a single slave device in Honeywell PGM Profibus loop? Keeping the other 5 device intact and working normal.

Yes, of course. As stated before, you will have to modify the Profibus configuration of both the slave (with its new analog ,modules) and the master, for every change in the network partners. But that involves a download of the new configuration to the slave (to integrate the new I/O modules), and to the Profibus master (for the changes in data exchange areas). Both will have to be stopped at that moment (hardware modifications often require that the PLC be stopped, and restarted when the modifications are complete).

c) Considering all the 6 slaves are connected in daisy chain, how can we disconnect one PLC slave without affecting other 5 slaves?

You are daisy-chained using Profibus cable and standard Profibus connectors? You can simply disconnect the Profibus connector from the S7-300 slave, and the connection to the rest of the network will be maintained, since the connector links the incoming cable to the outgoing. Expect bus fault messages and LEDs on the master when communications with the slave is lost.

One exception: if you are at the endpoints of the network (there will be only one cable connected to the connector in this case) then your termination circuit should be ON on that module; removing the Profibus cable would mean that the termination circuit is no longer powered (5V is provided to the circuit by the slave's interface) and the whole network would crash. Make sure that you set the next module's termination to ON (active) before you remove the first slave's connector, in that case.

Hope this helps,

Daniel Chartier

@dchartier

Thank you very much