Hi Ali,
SRX5400E/5600E/5800E (E stands for Enhanced ) can support SRX5K Enhanced Switch Control Board and SRX5K Enhanced Switch Control Board. SRX5400/5600/5800 not compatible with SRX5K Enhanced Switch Control Board and SRX5K Enhanced Switch Control Board. Midplane brings in the diffrence between SRX - 5400 and 5400E , 5400E got enhanced midplane.
Please go through link below.
http://www.juniper.net/assets/us/en/local/pdf/datasheets/1000254-en.pdf
Regards
ckishor
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