What is the slot access capacity on OSN 7500?

They have different FEC Encoding:
TN54NS4: HFEC/SDFEC
TN56NS4: SDFEC
TN57NS4: HFEC/SDFEC2
TN58NS4: SDFEC2
2, TN58NS4 occupies one slot on OSN 8800, and other NS4 boards occupy two slot. https://www.thunder-link.com/TN54NS4T01_p546.html

OSN7500 slot access capacity is different when equip with different Cross-Connect Board
Huawei osn 7500 MSTP transmission sytem Thunder link com

Huawei OSN7500 is a STM-64 level MSTP, It have 22 service slots and can MAX support 28*STM-64 interface. OSN7500 Subrack comes with two T1PIU (Power Interface Unit), one T1UX (System Auxiliary Interface Board), others system board and service board are configurable.

In the OSN 1500B subrack, slots 11-13 can be divided into half-width slots. Slot 11 can be divided into two half-width slots numbered slot 1 and 11, slot 12 can be divided into two half-width slots numbered slot 2 and 12, and slot 13 can be divided into two half-width slots numbered slot 3 and 13.

Yes, most of OSN7500 service board, you can use newer version to replace old ones, here listed some ordinary substitution boards below, or you can contact Thunder-link.com technical sales team to confirm the board substitution relation.

Huawei OSN7500 is a STM-64 level MSTP, It have 22 service slots and can MAX support 28*STM-64 interface. OSN7500 Subrack comes with two T1PIU (Power Interface Unit), one T1UX (System Auxiliary Interface Board), others system board and service board are configurable.

Huawei OptiX OSN7500 slot access capacity is different when equip with different Cross-Connect Board,Slot access capacity of the OptiX OSN 7500 when the T1PSXCSA board is used.

Huawei SDH equipment including huawei metro series and osn series, in huawei metro series, have metro1000 metro2050, metro3000, metro5000, osn series have osn1500, osn2500, osn3500, osn7500, is now mainly used osn series, you can see in thunder-link website.