Adding 7i73 to working setup 5i15 7i77 7i84

Hello all

I have a working config with 5i25 with one 7i77 connected to it and 7i84 connected to the 7i77 RS422 pins

is there a way to connect 7i73 pendant interface to this configuration without adding 7i74 8 channel RS422 interface card?

Its awkward to add just one additional RS-422 port

I can be done with a single external chip (a SP491 for example)
or using a Mesa 485X1 TTL to RS-422/485 adapter but it
would need to be hand wired to the second 5I25 I/O connector

I got a board with AM26LS31 - Quadruple Differential Line Driver, datasheet says
AM26LS31 family of devices is a quadruple complementary-output line driver designed to meet the requirements of ANSI TIA/EIA-422-B

no problem with wiring it to the 5i25 second port, will I need different firmware file for it?

You need a differential receiver also:

FPGA TX PIN ==> DIFF DRIVER ==> TX+ and TX- ==> 7I73 RX
FPGA RX PIN <== DIFF RECEIVER <== RX+ and RX- <== 7I73 TX

If you add a 26LS32 you can make a 4 channel adapter
or if you want a single chip for RX and TX , a SP491 or equivalent
transceiver will work.

Note that you cannot use 8 pin RS-485 transceiver chips

You can use the 7I77_7I74 firmware

Thanks, forgot about receiver side,

I got MAX 491 , its just slower than SP491 .... 2.5Mbps max

Will try it, if nothing will order the 7i74 and put both 7i73 and 7i84 on it

I cant seem to get it to detect the 7i73 , correct firmware is loaded in 5i25, if connected to the 7i77 rs422 port its detected right away, added sserial_port_1=00000000

MAX491 is connected like this

5i25 Port2 MAX491 7i73
pin1 --- MAX491 pin 2
pin3 --- MAX491 pin 5
MAX491 pin 12 --- RJ45 pin 6
MAX491 pin 11 --- RJ45 pin 3
MAX491 pin 10 --- RJ45 pin 1
MAX491 pin 9 --- RJ45 pin 2
5v ---- MAX491 pin 14,4 --- RJ45 pin 7,8
GND

---

MAX491 pin 6,7,3 --- RJ45 pin 4,5

I think the RX and TX polarities are reversed,
So swap RJ45 1,2 and 3,6

Peter thanks for the effort, it works !

Bringing this topic back from the dead........... I am looking to build the same setup:

6I25 7I77 7I84 and 7I73
I am fine with buying the 7I74 interface but am unclear on how / where  it gets interfaced to the system.

Thanks in advance.

Erik

The 7I74 connects to the second 6I25 expansion connector (P1)