Wednesday, 16 January 2019

Introduction to SECS/GEM - Beginner's Guide - Introduction to SEMI E37 HSMS

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Introduction to SECS/GEM - Beginner's Guide
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HSMS is the transport layer built on top of the TCP/IP protocol and it is intended as an alternative to SEMI E4 (SECS I) for applications where higher speed communication is needed or when a simple point to point topology is insufficient.

TCP/IP Settings

As HSMS protocol is derived from TCP/IP, the following settings are required for both Host (client) and Equipment (Server):

  • ConnectionMode: ACTIVE/PASSIVE Mode. ACTIVE Mode is normally on the Host side while PASSIVEMode (Listening) is on the Equipment side. However there is no restriction to use it vice versa.
  • Local IP Address and PortNumber: Required for any entity operating in PASSIVE mode. Determines the address on which the local entity will listen for incoming connection request. Typically Equipment is operating in this mode.
  • Remote IP Address and PortNumber: Required for any entity operating in ACTIVE mode. Determines the address of the remote entity to which the local entity will attempt to connect. Typically Host is operating in this mode.

HSMS Timeout Settings

Implementations of HSMS must provide for installation time setting of the following parameters.  The range and resolution of all parameters must be at least as shown in the table.

Parameter Name Range Typical Settings SEMI - SECS/GEM
T3 Reply Timeout 1-120 secs 45 secs Reply timeout.  Specifies maximum amount of time an entity expecting a reply message will wait for that reply
T5 Connection Separation Timeout 1-240 secs 10 secs Connection Separation Timeout.  Specifies the amount of time which must elapse between successive attempts to connect to a given remote entity
T6 Control Transaction Timeout 1-240 secs 5 secs Control Transaction Timeout.  Specifies the time which a control transaction may remain open before it is considered a communications failure.
T7 Not Selected timeout 1-240 secs 10 secs Time which a TCP/IP connection can remain in NOT SELECTED state (i.e., no HSMS activity) before it isconsidered a communications failure
T8 Network Intercharacter Timeout 1-120 secs 5 secs Maximum time between successive bytes of a single HSMS message