Honeywell HC900 Modbus TCP problems on 100Mbps network


Thread Starter

Alfred Monticello

We have an HC900 Honeywell controller. It has two 10/100Mbps network modules. E0 is tied to a Windows XP computer running SpecView using a directly connected straight through cable. The other port, E1, is connected to a Cisco 3524XL switch.

This E1 port is hard configured for 100Mbps-FDX, though we have tried 10Mbps-HDX.

We are seeing issues where the controller will hang, the network ports become unresponsive and sometimes the controller sends corrupted Alarm E-mails to our E-mail server on the TCP/IP network.

Am I seeing a negotiations problem with Modbus TCP trying to run on our TCP/IP network?

We are running the very latest honeywell HC900 firmware, which is 4.4.
Are you sure your ethernet switch is connected to a host RJ45 port and not an I/O RJ45 port?

The HC900 Installation and User Guide is here:

Note the network diagram on Page 17 (all pages pdf page numbers). Not all RJ45's have the same functionality.

You didn't mention which model controller you're working with and it makes a difference.

On the C-50 and C-70 controllers, the upper ethernet RJ45 connector is for LAN networking, whether to your PC with Specview, a 2nd HC-900 controller or your SMTP server for email (all through a switch, of course).

The lower RJ45 connector labeled I/O is the I/O link connection and is for HC900 remote rack I/O connections ONLY. It is not for generic LAN functions (not for Modbus TCP, Specview, email whatever). The caution message at the bottom of page 21 states:
"Likewise, no devices other than the HC900 components should be connected to the I/O link

Switch. Failure to comply will cause communication failures on the I/O link causing I/O modules to go in and out of their failsafe settings."

The C70 controller has a 2nd host ethernet port, labeled E2.

The controller module graphic on page 30 defines the ports:
- E1 is for LAN connections: a switch to which the PC with Specview, the SMTP email server

- E2 is a 2nd ethernet host \

- the RJ45 port labeled I/O is the remote I/O rack link connection, exclusively for (ethernet switched) HC900 scanner modules in remote racks.

You mention Modbus TCP/IP network. Is something other than Specview getting data from the HC?

Alfred Monticello

It is a C70. The upper RJ45 is E1, and it is directly connected to the SpecView computer. The lower RJ45, which is E2, goes to our Cisco switch.

Looking at page 30, this should be the correct configuration, since they are both ethernet ports. Our SpecView computer has two ethernet ports as well, one going to the HC900 E1 port, and the other goes to our Cisco switch. I'm wondering if there might be some crosstalk going on between the two networks on the SpecView computer, and the HC900 is seeing more than 10 nodes, causing it to hang and shut down.

Honeywell tells me the problem might be firmware, as there appears to be a lockup issue when sending E-mail alerts, which is what we are experiencing. It is supposed to be addressed in firmware rev 4.401 which is due out next month.

i think you are using the C70R controller. this controller have the 2 port as E1 and E2,

so E1 has the IP address

and E2 address is so please check the IP address of your PCs also on the same network .
been through this with a new C50... contacted tech support and they sent me a dummy program to load in the controller. It was just a new blank program to download to reset controllers memory, it seems like it worked cause that was October and no more issues.