STATUS SCIENTIFIC CONTROLS
Installation, Commissioning & Routine Gas Testing
FGD10A Oxygen / Toxic Gas Detector
TD18/002
Issue:
16
Change Note:
1904
Page 38
7.
C
OMMUNICATIONS
P
ROTOCOL
The communications protocol used by the FGD10A is used for
communications between devices connected via an RS232 connection at
19200 baud, 8 data bits 1 stop bit, no parity. This point-to-point, P2P,
protocol is a frame-based protocol.
7.1. Hardware connections
PC 9-
way ‘D’ connector
FGD10A connection
2
Tx
3
Rx
5
0V
PC 25-
way ‘D’ connector
FGD10A connection
3
Tx
2
Rx
7
0V
7.2. Control Byte Constants
The following control byte constants are used in the P2P protocol
1
.
Read, RD
= 0x13
(00010011)
Data Link Escape, DLE
= 0x10
(00010000)
Write, WR
= 0x15
(00010101)
Acknowledge, ACK
= 0x16
(00010110)
Negative Acknowledge, NAK
= 0x19
(00011001)
Single Data Frame, DAT
= 0x1A
(00011010)
End of Frame, EOF
= 0x1F
(00011111)
Write Password 1, WP1
= 0xE5
(11100101)
Write Password 2, WP2
= 0xA2
(10100010)
