RS485 connection to ESPEC climate control chamber

[K C]

Hi,

Now I see that is the third and fourth connection in your previous reply. Sorry,

No other thoughts at this moment.

Kees

[ShellTox]

Thanks for your time KC.

I will try to contact the manufacturer about this problem.

Meanwhile if anyone has any other idea, please post it.

[bjhmlx]

Hello together,

I got the same issue as ShellTox, i tried all possible combinations, but no communication functional with our espec temperature chamber.

I checked the DC voltages of the Txd and Rxd channels:

On the NI RS485-USB adpater i measured appr. 3.3V per channel. On the chamber RS-485 port I measured only 260mV on the Txd channel and 930mV on the Rxd channel. As far as I know the lower spec limit is 1,5 V? Can that be the problem? We have other espec hardware in our lab, the second chamber has got the same strange voltages.

Can anyone please give me a hint what else can be the issue?

Many thanks for your help!

Bjoern

[Jacobson-ni]

Bjoern,

The thread you replied to has not been commented on in a while.  I think you would get a much better response if you were to make a new post describing your issue.

[sockmonkey]

I know this is an old thread, but it may help someone. We have 2 Espec chambers and they are both RS-232. One connects with just RX, TX, and GND. The second chamber had to have DTR connected to DSR, and RTS connected to CTS. If you have tried everything and still have no connection try shorting DTR to DSR, and RTS to CTS on the chamber side.

[K C]

Hi,

Add DCD to the DTR-DSR connection. 

Kees

[engineerd007]

I ran into the same issue with RS485 communication with my Espec SH-241 temp/humidity chamber.  Connected a USB to RS485 adapter, but couldn't communicate with the chamber using the Putty serial terminal.  I tried several different wiring configurations in case they were mislabeled by either Espec or the RS485 adapter manufacturer.  None worked. 

Thought it might be that my RS485 adapter only supported half duplex mode (China user guide hard to decipher), so I ordered a US designed adapter that called out full duplex support. Still not communicating with the chamber.  

Exchanged several emails with Espec support and they finally communicated the delimiter need for the Espec chambers.  

The root issue ended up being two fold:

1. The Espec chamber expects a specific delimiter (\r\n), which is not detailed anywhere in their user guide, programming guide, RS485 communication guide, etc.  
   1. Example:  "1,MON?\r\n"
2. Putty doesn't provide a very straight forward mechanism to specify the delimiter.  I was never able to configure Putty to send the commands appropriately.  
   1. The Termite serial terminal app provides straight forward delimiter settings that worked without issue.  Realterm can be configured to work as well, but Termite is a bit more intuitive.  

Went back to my original wiring config (SD+/RD+, SD-/RD-) with new RS485 adapter and Termite with delimiter and VOILA comms were working.  Verified similar operation with my first RS485 adapter and it worked as well.     

Hope this helps!  

[untitle01]

Hi engineer007,

Can you please show us your RS485 to USB or RS485 adapter? We are having hard time to find one.

For the delimiter, I think you can set it up. There are 3 option. CL, L, and C.