COM Port Redirection

Some ACP customers have found they can save a good deal of money by combining their serial I/O with their user display in the form of a Thin Client with multiple high-speed serial ports.

If there is a remote location that needs serial I/O, one option is to install one of the serial to Ethernet boxes, often called "Serial Port Servers" or even "Terminal Servers", because they can serve serial data to other computers over standard Ethernet. The most well known company making these devices is Lantronix, who makes serial to Ethernet converters in a large number of formats. A device with a single serial port (such as the MSS100) has a list price of $499. They also sell this product in a four-port model (the MSS4-D-01) with a list price of $795. If you want 6 ports, you can either build it up out of several different devices or move to a product such as their ETS8P. This device does offer 8 ports, but requires special cables, license software, and carries a list price of $1,495 without any of these accessories. It only supports RS-232, so if 422 or 485 are required a converter is needed.

Compare this with a solution available from ACP - a full functioning Thin Client that also allows users to remote high-speed serial I/O. With a unit like the Advantech 5820, a small form factor full industrial device can be placed wherever Ethernet cable and 5V DC are available. Standard with its list price of $625 the unit comes with 2 serial ports. For an extra $125 it can be expanded to 6 full DB-9 ports that support a mixture of 232/422/485. If something other than talking with a low priority serial device like a hand scanner is required, consider adding our high-speed serial module. This adds only $150 (bringing the total list price to $900) and will even allow the unit to run PLC programming software. When combined with the ThinManager license the price for these 6 remote ports AND a Thin Client is still less expensive than a 6 port solution from Lantronix.

Communications on the plant floor between data acquisition systems and IO devices is critical. ACP's high-speed serial driver is the only COM port communications software available that is capable of driving reliable serial transmissions through a Thin Client device and back to the terminal server. Standard ICA and RDP serial communications through Thin Client devices has been tested by ACP in production and failed at two separate locations. In one case the ICA and RDP COM protocols were tested for communications to S5 series PLCs from Siemens, and in a second case the device was a high-speed scanner. For this reason ACP has created a high speed reliable communications module for use with all ACP enabled Thin Clients, which is fully capable of supporting these and other critical COM functions.

ACP did some testing on a Celeron 400 MHz server running Windows 2000 Server and using MetaFrame 1.8 (required to allow the CE clients to run with the ICA Protocol - ACP ThinManager already includes this protocol). Two Thin Clients systems were tested - a standard Windows CE Thin Client and an ACP Enabled DC-40-100 Thin Client, both with the same speed processor and both using the ICA protocol from Citrix. The accuracy (Incompletes) and ability to keep up with the set baud rate (Timeouts) of each transmission were monitored. Three samples of each baud rate and update speed were tabulated and the averages recorded in the table below:

ACP's is the only Thin Client architecture that allows for the expansion of client device platforms to support multi-port serial cards. ACP partner manufacturers, including Advantech, Contec, HMW and Ann Arbor provide enabled Thin Clients with available expansion slots for multi-port COM adapters. When used in connection with ACP's high speed serial module this provides for more than the standard 2 or 3 com ports provided by all competitors.

For more information on ACP Industrial Thin Client computers, please visit our web site at http://www.thinmanager.com

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