Every RAIL and SAFE modules fulfil the standard DIN EN 61000-6-2 (interface resistance).
That means that the communication "bus line" is proved for an interference resistance +/- 1kV
capacitive load . Modules with firmware <2.1 had a tolerance in the inerference resistance up to
Modules with the firmware 2.1 and 2.2 will actually interrupt the working condition if the EMC influence
in the communication bus line is higher than 3 kV.
Problem description with firmware version 2.1 and 2.2
All RAIL modules with firmware 2.1 and 2.2 can have a communication conflict. They have been de-livered approximately from June 2002 till now. The RAIL modules can stop their running mode and freeze itself in stop condition. The stopped mod-ule can only be reconditioned to running mode by a manual replacement of the power supply! The stopped working condition appears due to a new integrated processor that has a lower EMC (electro magnetic compatibility) tolerance than in module series with firmware lower 2.1. Modules with integrated new processor:
PCD7.L100 , PCD7.L110
PCD7.L121 (SAFE module with new functionalities)
Every RAIL and SAFE modules fulfil the standard DIN EN 61000-6-2 (interference resistance)! That means that the communication bus line is proved for an interference resistance +/- 1kV (capaci-tive load). Modules with firmware <2.1 with the former processor and less features had a tolerance in the inter-ference resistance up to approximately +/- 4kV (remember: the proved and official resistance is +/- 1kV). Modules with firmware 2.1 and 2.2 will actually interrupt the working condition if the EMC influence in the communication bus line is higher than 3 kV.
Short term solution
If there are some modules which indicate the described failure, the following improvements are possi-ble: 1. The bus line should be installed as described in the RS485 manual (26/740) to be sure that the bus line is free of any electromagnetic compatibility (EMC) influence. 2. With adding two external “Varistors” (Type: SIOV S07 K60) in the busline according to the drawing below at every single module, it is possible to increase the EMC interference resistance to +/ - 4.5kV.
Varistor type: Disc-Varistor SIOV S07 K60
Possible Distributor: EPCOS AG (international) Homepage: www.epcos.com
Ordering code: B72207-S600-K101
Varistors are usually available in every electronic components store!
With use of external Varistors is it possible that some S-Bus telegrams go lost. The higher the baudrate and the more bus members are involved, the higher the probability to loose telegrams.
Therefore we do not recommend to use a communication baudrate of 38’400 baud if the project has long distances, more than 50 S-Bus members and if external varistors are added!
Long term solution
The supplier BTR is about to improve the EMC interference resistance up to +/- 4.5kV of the module types mentioned above. This requires a modification of the module manufacturing process. The new modules will have an integrated interference resistance of around +/- 4.5kV without any restrictions.
PCD7 / Lxxx
Last update: 27.05.2015 16:54
First release: 22.06.2004 11:35