The YASC2, YASC6 and YASC8 are TTL/232 interfaces.
The RS232 side is wired as a DTE to a DB9M connector.
Nothing much amazing here, except that the PCB is pretty small, and the interface circuit provides real RS232 levels, not transistor-shifted almost-RS232 levels. I've experienced compatibility problems with that scheme before, so I'm just using a real charge-pump type interface chip now.
So far, I'm planning to use these with my 8upShield and 8upPiShield, as part of some automated test-fixtures and industrial-control applications.
The YASC485 is a bit different. It has the typical RS485 transceiver chip (SN75176-compatible), but the same PCB can be built with either a DB9F or an RJ45. The TTL-header side is compatible with YASC2/6/8, and of course my 8upShield/8upPiShield.
The YASC485D is very similar, but has 2 RJ45 connectors, thus allowing the RS485 but to be looped-through. Critically important for multi-device RS485 "networks". There's a little termination (100-ohm) slide-switch which would be externally accessible (if you mounted this on a panel).
On the YASC485(D), the RJ45 connector is wired to my own proprietary pinout, which is compatible with many other industrial-control widgets I've put together over the years (again, no rocket-science here):
Pin 1 = RS485(+) serial link.
Pin 2 = RS485(-) serial link.
Pin 3 = Connected to pin-3 on the 2nd RJ45 port.
Pin 4 = GND.
Pin 5 = GND.
Pin 6 = TTL-open-drain, bidirectional signal. For "/IRQ" or other purposes.
Pin 7 = VBUS. (typically 5-48VDC range, or as req'd by your application)
Pin 8 = VBUS.
The RS485 differential pair normally requires a 100-ohm termination, as would be typical for a CAT cable interface. On the YASC485 the termination is permanently connected. On the YASC485D there's a little slide-switch to turn the termination on/off.
The VBUS/GND signals are intended for "remote power". In my industrial control applications, VBUS is always 24VDC. However, it could easily be anything you need - from 5-48VDC. Just make sure the devices on your bus can take that voltage!
On the YASC485(D) boards there are two 2-pin screw-terminal blocks:
VBUS-IN terminals = Connect a power source here (5-48VDC), and this will be directly connected to the VBUS/GND pins on the CAT cable. This is how you supply power TO the bus.
VBUS-OUT terminals = Diode-coupled to the VBUS/GND pins on the CAT cable. This is a power output - where you would attach the local device you would like to be powered FROM the bus. Remember there's a schottky-diode here, so your output voltage will be slightly lower (approx 0.4-0.6V) than what you measure on the CAT cable.
Note that I've chosen the data and power pins to be compatible with typical "POE" type equipment. If you have a "Dumb POE injector", it would very likely be perfectly compatible with these boards (YASC485(D)) and all other devices similarly wired. There is no 802.3af-style identification on my board - so you CANNOT use the more expensive "smart POE injectors". BEFORE you commit to using any "POE" rated gear with a YASC485(D) board - check carefully regarding pinout and compatibility. I do NOT guarantee success.
Controlling the YASC485(D) transceiver direction:
"RTS" from your host device = Enables the transmitter when high (1).
There is a config-jumper which allows options for the receiver-output control:
A) Receiver output controlled by RTS (1 = transmit mode, 0 = receive mode).
B) Receiver output controlled by DTR (1 = receiver off, 0 = receiver on).
C) Receiver always on (jumper out).
Check the schematics - I'm sure these options will be self-explanatory.
Also, regarding the bidirectional signal on pin-6 (/IRQ or whatever you want):
D) DTR can be used for controlling the open-drain to the pin-6 output.
E) DSR or CTS can be used for reading back the buffered pin-6 input.