SEMI E37 — HSMS
SEMI E37 defines the TCP/IP transport commonly used for SECS-II traffic, including session selection, data messages, control transactions, timers, system bytes, and connection recovery.
Area
Communications
Profile coverage
200 mm Tool Standards · 300 mm Tool Standards · 300 mm Overhead Automation
Purpose
HSMS replaces the serial block-transfer concerns of SECS-I with a network-oriented service while preserving SECS-II content. It standardizes how endpoints establish a selected session and correlate primary messages with replies.
Where it applies
E37 is the normal transport choice for modern GEM interfaces on Ethernet networks. An implementation still needs a defined active or passive role, addressing, session settings, timeouts, reconnect policy, and customer-approved network configuration.
Who implements it
Both endpoints implement HSMS framing and control behavior. Equipment software usually owns connection lifecycle, selection state, timers, pending transactions, system-byte allocation, link tests, and safe recovery after transport loss.
Relationships and dependencies
- Transports SEMI E5 SECS-II messages.
- Commonly carries SEMI E30 GEM and GEM300 services.
- Replaces E4 for most modern network-connected equipment interfaces.
Practical implementation guidance
- Keep socket state, HSMS selection state, and GEM communication state distinct and observable.
- Use thread-safe transaction correlation and fail outstanding requests promptly when a session drops.
- Test simultaneous sends, duplicate system bytes, link tests, timeout recovery, and abrupt disconnects.
Common mistakes
- Reporting “connected” when TCP exists but the HSMS session is not selected.
- Blocking the UI thread while waiting for a connection, selection, or T3 reply.
- Reusing system bytes while a matching transaction is still outstanding.