An RTM for the
CONV-TTL-RS485 board has already been designed and tested. It is a 6
channel RTM with each channel capable of receiving one input in RS485
and repeating it on 3 outputs.
This RTM uses LEMO 0S connectors with 2
pins.
_Side-by-side are the current CONV-TTL-RS485 RTM with LEMO 0S
interface
and a mock-up of the 2-channel version with D-Sub9 interface_
A new RTM design for the CONV-TTL-RS485 is being proposed to fullfill a number of user requirements:
-
User requirements (CERN specific):
- Most of the legacy boards to be replaced by the new generation repeaters, use a D-Sub 9 connector for the RS485/RS422 interface. The proposed LEMO 0S RTM is therfore not a drop-in replacement.
- The use of the RS485 protocole is mainly required in fanout topologies, where one signal must be propagated to multiple locations. The 6 channels on the LEMO 0S RTM, although offer 3 outputs each, still need to be manually daisy-chained in order to offer a maximum number of output signals.
-
Proposed solution
- Design a new RTM with D-Sub 9 interface for I/O.
- The RTM will repeat 2 channels of the 6 available from the conv-ttl-rs485 board.
- Each of the two channels will repeat the input signal on 5 output ports (Limited by the physical size of the RTM Piggyback panel).
- The RTM must be designed in the piggyback format, similar to
the LEMO 0S RTM,
in order to be mounted on the same RTM
motherboard
used for CONV-TTL-RS485 and CONV-TTL-BLO RTMs.
Denia Bouhired, 21 Septembre 2017