From Technologic Systems Manuals
Product Page

1 Overview

The TS-SER2 is an 8-bit PC/104 daughter card (standard format) that provides 2 RS-232 serial ports and 1 parallel port.

2 Getting Started

See your SBC's PC104 section for information on the ISA 16550 driver and getting a connection to the COM device.

3 Serial Ports

The two serial ports are labeled COMA and COMB. RS-232C drivers are standard, but RS-422 (a.k.a. full-duplex RS-485) / RS-485 drivers can be added optionally.

With either set of drivers, all serial signals are routed to both 10-pin headers and RJ45 connectors. See tables 1 and 2 for pin-outs. The RJ45 pinout for RS-232 is per the industry standard EIA/TIA 561 specification. The RJ45 socket pins are numbered from left to right (1 through 8) when looking into the socket.

The serial ports use 16C550 UARTs, which provide 16 byte send and receive FIFOs, reducing the CPU overhead of high-speed serial communications.

For half-duplex RS-485 you must enable and disable the transmitters when sending data. This is done using the RTS line of the serial port. Asserting RTS turns on the transmitter, and deasserting RTS turns it back off. Note that RTS still controls the transmit enable when using fullduplex RS-485, so make sure to assert RTS. If you require automatic transmit enable, please contact Technologic Systems.

The serial baud clock is generated from either the PC/104 BCLK (8.33 MHz) or OSC (14.318 MHz) signals, selected by JP13. If you are using the TS-SER2 with a Technologic Systems EPC board, you should use the BCLK selection (JP13 installed). If you are using another manufacturer’s processor board and you do not know the PC/104 BCLK rate, you should use the OSC selection. Because a programmable logic device generates the baud clock, non-standard clock rates can be handled if necessary in your design. Please contact Technologic Systems for further details.

Port COM A can use interrupts 3, 5, and 7. COM B can use interrupts 4, 6, and 9. To select the desired interrupts, simply install jumpers on the associated pins in the IRQ jumper block.

3.1 Serial Port Header Pin Location

Pin 1 is away from the PC/104 connector.

05 04 03 02 01
10 09 08 07 06
Note: Not all serial adapter cables are alike! We are aware of at least two 'standard' pin outs for these cables. If you did not purchase your serial adapter cables from us, this may be an issue if the serial ports are not working correctly (or at all)

3.2 Serial Port Header Pinout

Pin COMA/B (Header and DB9)
RS-232 RS-485
1 -- TX+
2 RX data
3 TX data
4 Logic High (DTR)* RX+
6 -- RX-
9 -- TX-
10 --
Note: Resistor pull-up to 5V on ten pin header

3.3 RJ45 Pinout for RS-232, Full Duplex RS-485, and Half Duplex RS-485

Pin COMA/B (RJ45)
RS-232 FD RS-485 HD RS-485
1 -- TX+ RX/TX+
2 -- TX- RX/TX-
3 -- -- --
5 RXD -- --
6 TXD -- --
7 CTS RX- --
8 RTS RX+ --

3.4 JP Jumper Functions

JP# Description Port
JP1 Select FD RS-485 (RS-422 - 2 wire pairs) COMA
JP2 Select HD RS-485 (1 wire pair) COMA
JP3 Add termination resistor to TX pair COMA
JP4 Add termination resistor to RX pair COMA
JP5 Connect CTS to RJ45 connector COMA
JP6 Connect RTS to RJ45 connector COMA
JP7 Select RS-422 (2 wire pairs) COMB
JP8 Select RS-485 (1 wire pair) COMB
JP9 Add termination resistor to TX pair COMB
JP10 Add termination resistor to RX pair COMB
JP11 Connect CTS to RJ45 connector COMA
JP12 Connect RTS to RJ45 connector COMB
JP13 Select PC/104 Bus Clock as baud clock source (PC/104 OSC used if not installed) COMA & COMB

3.5 Serial Port I/O Address Selection

On On On 2e8 3e8
On Off On 2f8 3f8
Off On On 260 268
Off Off On Disabled Disabled
On On Off 250 258
On Off Off 220 228
Off On Off 210 218
Off Off Off Disabled Disabled
Note: JP18 is shared with the parallel port

Because the I/O address decode is handled by a programmable logic device, completely different addresses can be used if necessary in your design. Please contact Technologic Systems for further details.

Table 5 lists the de-facto ‘standard’ I/O addresses and interrupts for PC compatible computers. Note that this setup shares IRQ 4 between COM1 and COM3, and IRQ 3 between COM3 and COM4. You cannot use interrupt driven serial communications simultaneously on both ports using the same interrupt. Because of this, the factory default settings are IRQ 5, address 2E8h for COMA (COM4) and IRQ 6, address 3E8h for COMB (COM3).

3.6 Standard Serial Port I/O Addresses

Port # I/O Address Standard IRQ Factory Default IRQ
COM1 3F8h 4 4
COM2 2F8h 3 3
COM3 3E8h 4 6
COM4 2E8h 3 5

4 Parallel Port

The parallel port is a standard PS/2 mode bidirectional port. It can be assigned to 5 different I/O locations or disabled completely. The parallel port can use interrupts 7 and 9. To select the desired interrupt, simply install a jumper on the associated pins in the IRQ jumper block.

4.1 Parallel Port I/O Address Selection

JP16 JP17 JP18 LPT Address
On On On 278
On Off On 378
Off On On 3bc
Off Off On Disabled
On On Off 278
On Off Off 27c
Off On Off 37c
Off Off Off Disabled
Note: JP18 is shared with the parallel port